Where this unit fits in Prior learningThis unit builds on:ideas introduced in unit 4C Keeping warm and unit 5D Changing state in the key stage 2 scheme of work,unit 7I Energy resources, unit 7G Particle model of solids, liquids and gases, pupils will have encounteredthe particle model of matter.
The concepts in this unit are: temperature, expansion and contraction, thermal energy transfer.
This unit leads onto:unit 9I Energy and electricity, covering energy transfers and energy conservation.
To make good progress, pupils startingthis unit need to understand: • the particle model for solids, liquids
and gases • that energy can be transferred.
Framework yearly teaching objectives – Energy• Describe energy transfer as the result of temperature difference and use this to explain that:
– heating is a process where energy is transferred – temperature change is the response of the material to the energy transfer – radiation is a means of energy transfer which does not directly depend on the movement of particles.
• Use the particle model of solids, liquids and gases and energy transfer to explain: – the processes of conduction, convection, evaporation – what happens when substances change state – the performance of thermal conductors and insulators.
Expectations from the QCA Scheme of Work At the end of this unit …
… most pupils will … … some pupils will not have made somuch progress and will …
… some pupils will have progressedfurther and will …
in terms of scientific enquiry NC Programme of Study Sc1 2c, d, g, h, i, j, k, l, m, o, p
• plan a survey of perceptions of temperature, using anappropriate sample
• plan an investigation into methods of reducing heat loss • carry this out using ICT for recording temperature data
and relate findings to practical implications • select effectively information from secondary sources to
compare methods of preventing heat loss in houses • collect and interpret temperature data from a substance
changing state.
• use thermometers safely • present survey data using a chart or table • identify and control key variables in an
investigation of insulators for reducingheat loss and draw practical conclusions
• select information to report on ways ofreducing heat loss in houses
• draw a graph of temperature changeswhen a substance changes state.
• make systematic measurements oftemperature changes with a precisionwhich enables reliable conclusions to bedrawn in an investigation of insulators
• evaluate different sources of informationon domestic heat loss prevention methods
• extrapolate from temperature data onchange of state.
in terms of physical processes NC Programme of Study Sc4 1a, b, d, 2c; Sc4 5d, e, f
• give examples of common temperatures on the Celsius scale • distinguish between heat and temperature • describe energy flow as the result of temperature difference • describe some uses of good conductors and insulators and
examples of conduction in solids and convection in liquidsand gases
• explain conduction and convection, expansion and changeof state in terms of the particle model.
• give examples of some commontemperatures
• describe some uses of good conductorsand insulators;
• describe how insulators can reduce heatloss
• describe how substances expand andchange state.
• give examples of a wide range oftemperatures on the Celsius scale
• compare conductivity of materials andrelate this to their uses
• use the particle model to explain changeof state relating this to the forcesbetween particles.
Suggested lesson allocation (see individual lesson planning guides)Direct route
I1 Whattemperature?
I2 Temperatureand energy
I3 Bigger andsmaller
I4 All change
I5 Conduction
I6 Convection
I7 Evaporation,radiation
Additional informationThe emphasis in some of these lessons may well depend on the time of year, whether keeping warm or cool seems most important to pupils at the time.
MisconceptionsPupils frequently believe that particles expand, rather than get further apart; and that liquid particles are further apart than solid ones. The averagespacing is increased but this is because the liquid particles are arranged randomly.
Health and safety (see activity notes to inform risk assessment)Many of the practicals involve heating objects. Normal laboratory safety practice is required but care should be taken as heated objects (metal bars,tripods) do not look hot but may remain so for some time.
I8 Explaining the results –Think about variables
Extra lessons (not in pupil book)
Review and assess progress(distributed appropriately)
Learning objectivesi Our perceptions of ‘hot’ and ‘cold’ are subjective. ii Thermometers allow us to measure temperature objectively.
Scientific enquiryiii Different types of thermometer are used to measure temperature.
Suggested alternative starter activities (5–10 minutes)
Introduce the unit
Unit map for Heating andcooling.
Share learningobjectives
• Find out why we needthermometers.
• Be able to use differentkinds of thermometers.(Sc1)
Problem solving
Use feeling in hands todecide how hot a bowl ofwater is to demonstrate theneed for a standard scale.
Capture interest (1)
Show differentthermometers, discuss their uses. Or use photos.Catalyst InteractivePresentations 2
Capture interest (2)
Show photos of differentscenarios relating toheating and cooling.Catalyst InteractivePresentations 2
Suggested alternative main activitiesActivity
Textbook I1
Act I1a Practical
Learningobjectivesee above
i, ii and iii
i
Description
Teacher-led explanation and questioning OR pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
Making a thermometer Pupils make a simple water thermometer anduse it to measure temperature.
Approx.timing
15 min
20 min
Target group
C H E S
R/G G R S
✔ ✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
Pupils discuss why we needthermometers.
Sharing responses
Teacher-led discussion ofoutcomes from Activity I1a.
Group feedback
In groups, pupils listdifferent kinds ofthermometers, and saywhere each would be used.
Word game
Pupils play hangman withthe names of different typesof thermometer.
Looking ahead
Remind pupils of theparticle model by arranginggroups of pupils to model asolid and then a solid givenmore energy to vibrate.
Learning outcomes
Most pupils will …
• give examples of a range of temperatures onthe Celsius scale
• plan a survey of perceptions of temperature,using an appropriate sample
• realise that the sensation of cold is becauseenergy is leaving the skin and the sensation ofwarmth is because of energy entering the skin.
Some pupils, making less progress will …
• give examples of some common temperatures • use thermometers safely • present survey data using a chart or table • realise that you cannot use your skin to
measure temperatures reliably.
Some pupils, making more progress will …
• give examples of a wide range of temperatureson the Celsius scale
• also use thermometers with precision • also understand that cold is the absence of
thermal energy.
Key wordstemperature, degrees Celsius, ºC, thermal (heat) energy, energy, red only:absolute zero
Learning objectivesi Realise that there is a difference between thermal energy (heat) and temperature.
Scientific enquiryii Use a model to develop understanding. (Framework YTO Sc1 8a) iii Carry out experiments with two input variables (energy supplied and mass) and one outcome variable (temperature rise). (Framework YTO Sc1 7c)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Pupils work in pairs toanswer questions on thepupil sheet about differenttypes of thermometers.
Share learningobjectives
• Be able to explain thedifference betweenthermal energy andtemperature.
• Carry out an experimentwhere there are two inputvariables and one outputvariable. (Sc1)
Problem solving
Pupils suggest whether asteaming kettle or a bath isat the highest temperatureand which has the mostheat energy.
Capture interest (1)
Demo the food-burningexperiment with twodifferent quantities ofwater.
Capture interest (2)
Demo of different amountsof energy being put intothe same volumes of water.
Suggested alternative main activitiesActivity
Textbook I2
Activity I2a Practical
Activity I2b Catalyst InteractivePresentations 2
Learningobjectivesee above
i and ii
i and iii
Description
Teacher-led explanation and questioning OR pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
Energy and temperature Pupils find out how much energy is neededto heat different volumes of water by 10oC
Support animation to the ‘particles’ in beakers of water at differenttemperatures.
Approx.timing
20 min
30 min
5 min
Target group
C H E S
R/G G R S
✔ ✔ ✔
✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
Show the pupils thelearning objectives again.Ask volunteers to explainhow the lesson has helpedthem to achieve theobjectives.
Sharing responses
Pupils answer questionsabout Activity I2a.
Group feedback
In groups, pupils completethe sentences about thedifference between heat andtemperature.
Word game
Play the Taboo game.
Looking ahead
A small group of pupilsmodel a solid as heatenergy causes increasedvibration and expansion.
Learning outcomes
Most pupils will …
• realise that temperature change depends bothon the energy supplied and the number ofparticles present
• consider the interaction of more than oneinput variable (mass and energy transferred)to produce one outcome variable (temperaturerise).
Some pupils, making less progress will …
• know that supplying the same amount ofenergy does not always give the sametemperature rise
• decide which experiments need to be comparedto give a fair test.
Some pupils, making more progress will …
• also develop an understanding thattemperature is the average energy per particle
• also use their ideas about temperature topredict the outcome of experiments involvingheating.
Learning objectivesi Relate changes in temperature to changes in the movement of the particlesii Understand that expansion on heating can be explained in terms of the movement of particles.
Scientific enquiryiii Use the particle model to explain expansion. (Framework YTO Sc1 8a)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Pupils complete thesentences read out to themabout temperature andenergy.
Share learningobjectives
• Find out what happenswhen something is heatedor cooled.
• Describe some examples ofheating causing expansion.
• Use the particle model toexplain heating andcooling. (Sc1)
Brainstorming
Pupils suggest examples oftimes and places wherethings expand or contractwhen the temperaturechanges.
Problem solving
Demo how a tight screw capcan be taken off a bottle.
Capture interest
Demo the heating of abimetallic strip.
Suggested alternative main activitiesActivity
Textbook I3
Activity I3a Practical
Activity I3b Practical
Activity I3c Paper
Activity I3d Catalyst InteractivePresentations 2
Learningobjectivesee above
i, ii and iii
i, ii and iii
i, ii and iii
i, ii and iii
i, ii and iii
Description
Teacher-led explanation and questioning OR pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
Expansion in solids Pupils watch ball and ring and metal roddemonstrations of solids expanding and contracting.
Expansion in gases Pupils observe what happens to a column of airat different temperatures.
Expansion in liquids Pupils analyse results of liquids expanding bydifferent amounts and look at what happens when water freezes.
Support animation of particles in solid, liquid, gas as the substancesexpand.
Approx.timing
20 min
10 min
10 min
10 min
5 min
Target group
C H E S
R/G G R S
✔
✔
✔
✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
Pupils answer questionswith one (or two) wordanswers with white boards,or volunteer answers.
Sharing responses
Whole-class feedback onActivity I3a or Activity I3b.
Group feedback
Pupils produce a poster toexplain why a thermometerworks.
Learning objectivesi Know that the temperature of a substance stays constant during changes in state.ii Relate this to the particle model.
Scientific enquiryiii Measure temperature changes during changes in state and present the data using line graphs. (Framework YTO Sc1 7d, f)iv Use a scientific model to explain observed phenomena. (Framework YTO Sc1 8a)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Play ‘Give me five’. Askpupils to give five examplesof things that expand whenthey are heated, or contractwhen cooled.
Share learningobjectives
• Find out what happens totemperature as thingschange state.
• Be able to explain whathappens during a changeof state using the particlemodel. (Sc1)
Problem solving
Show a cooling curve forgold. Ask pupils to describewhat information they canget from the graph.
Capture interest (1)
Show a drink with ice cubesand a thermometer and askfor predictions about howlong this drink will stay atthe same temperature.
Capture interest (2)
Pupils are asked for theopposites of melt andcondense and to explain thedifference between meltand dissolve.
Suggested alternative main activitiesActivity
Textbook I4
Activity I4a Practical
Activity I4b Catalyst InteractivePresentations 2
Learningobjectivesee above
i, ii, iii and iv
i, ii, iii andiv
i, ii, iii andiv
Description
Teacher-led explanation and questioning OR pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
Changes of state Pupils observe a liquid turning to a solid andanalyse the cooling curve.
Support animation showing changes of state
Approx.timing
20 min
20 min
5 min
Target group
C H E S
R/G G R S
✔ ✔ ✔
✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
Pupils write definitions forwords relating to changes ofstate.
Sharing responses
Whole-class discussion ofthe outcome of Activity I4a.
Group feedback
In groups, pupils annotatethe graph and explain toeach other why thetemperature stays the same.
Problem solving
Ask pupils why a steamburn can be much moreserious than one fromboiling water.
Looking ahead
A small group of pupils lineup as particles in a solidand link arms, the end oneis heated and vibrates,vibrations are passed alongto model conduction.
Learning outcomes
Most pupils will …
• review their knowledge of the particle modelfor solids, liquids and gases
• with guidance, begin to use the particlemodel to explain changes in state
• collect and interpret temperature data from asubstance changing state.
Some pupils, making less progress will …
• begin to use the particle model to comparesolids, liquids and gases
• describe how substances change state • draw a graph of temperature changes when a
substance changes state.
Some pupils, making more progress will …
• use the particle model to explain change ofstate relating this to the forces betweenparticles
• also predict the shapes of graphs for heatingexperiments that involve changes in state.
Key wordsstates of matter, changes of state, red only: forces of attraction
Learning objectivesi Learn that thermal energy can be transferred from particle to particle.ii Relate this knowledge to the arrangement of particles in different materials.
Scientific enquiryiii Use models to explain thermal energy transfer by conduction. (Framework YTO Sc1 8a)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Play ‘It’s on the tip of mytongue’ with words forchanges of state.
Share learningobjectives
• Find out aboutconduction.
• Use the particle model toexplain conduction.
• Describe materials asconductors or insulators.
Problem solving
Show pupils some examplesof saucepans and ask themto suggest why they havemetal pans and wooden orplastic handles.
Capture interest (1)
Demo ice trapped by gauzeat the bottom of a testtube with a Bunsen burnerheating the water at thetop to boiling point.
Capture interest (2)
Volunteer pupils stir sugarinto beakers of very hotwater, one with a plasticspoon and one with a metalspoon. The class predictswhat the volunteers willfeel.
Suggested alternative main activitiesActivity
Textbook I5
Activity I5a Practical
Activity I5b Paper
Activity I5c Catalyst InteractivePresentations 2
Learningobjectivesee above
i, ii and iii
i, ii and iii
ii and iii
iii
Description
Teacher-led explanation and questioning OR pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
How quickly does heat travel? Demo of heat travelling along a bar,heating one end, seeing tacks held on by Vaseline or wax falling as itmelts.
House insulation Pupils explain why insulation in a house works.
Support animation in which pupils identify the good conductors andinsulators in a house.
Approx.timing
20 min
15 min
15 min
5 min
Target group
C H E S
R/G G R S
✔ ✔
✔ (✔ )
✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
Play ‘Give me three’ withexamples of conductors andinsulators.
Sharing responses
In pairs, pupils completesentences and comparetheir answers with anothergroup to summarise whatthey learnt from ActivityI5a.
Group feedback
In groups, pupils discussthe answers to Activity I5b.
Word game
Word search with conductor,insulator, then differentexamples; after findingwords pupils put them intotwo groups.
Looking ahead
Demo a spiral above smallBunsen flame, and askpupils to suggest why thishappens.
Learning objectivesi Learn that thermal energy can be transferred by the movement of particles.ii Relate this to the movement of particles in solids, liquids and gases.
Scientific enquiryiii Use models to explain thermal energy transfer by convection. (Framework YTO Sc1 8a)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Play ‘Tell me three thingsabout Activity I5a from thelast lesson’.
Share learningobjectives
• Find out about convectionin liquids and gases.
• Be able to explain it interms of particle theory.(Sc1)
Problem solving
Show pupils that theheating element is at thebottom of a kettle, but thecooling compartment is atthe top of a fridge.
Capture interest (1)
Demo the candle box toshow how smoke moves inconvection currents.
Capture interest (2)
Show video clips of thingsthat use convectioncurrents. Catalyst InteractivePresentations 2
Suggested alternative main activitiesActivity
Textbook I6
Activity I6aPractical
Activity I6bPaper
Activity I6c Catalyst InteractivePresentations 2
Learningobjectivesee above
i, ii and iii
i, ii and iii
i, ii and iii
i, ii and iii
Description
Teacher-led explanation and questioning OR pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
Convection in a liquid Pupils observe convection currents in aliquid.
Convection currents around us Pupils apply their knowledge ofconvection currents to everyday scenarios.
Support animation showing convection currents, particularly sea andland breezes at day and night time.
Approx.timing
20 min
15 min
10 min
5 min
Target group
C H E S
R/G G R S
✔ (✔ )
✔ ✔ ✔
✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
Play ‘Give me three’ and askfor differences betweenconduction and convection.
Sharing responses
Whole-class discussion ofActivity I6a.
Group feedback
In groups, pupils use theexperiments they have seento describe what aconvection current is, andwhy it happens.
Word game
Create a ‘poem’ based onthe word convection.
Looking ahead
Wipe a little surgical spirit/ethanol/water on pupils’skin, or wet one hand anddirect a cold fan at bothhands and observe thetemperature difference.
Learning outcomes
Most pupils will …
• recognise when thermal energy transfer ishappening by conduction
• know that convection requires the particles ofthe material to be moving
• know that moving particles set up convectioncurrents.
Some pupils, making less progress will …
• recognise common situation where heating andcooling happens by convection
• know that convection happens in liquids andgases but not in solids.
Some pupils, making more progress will …
• also explain convection currents in terms ofexpansion and density changes.
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Ask pupils to give someexamples of heat rising fromthe last lesson.
Learning objectivesi Learn that thermal energy can be transferred by the movement of particles during evaporation.ii Learn that thermal energy can be transferred in the absence of particles.
Scientific enquiry iii Use models to explain thermal energy transfer by evaporation and radiation. (Framework YTO Sc1 8a)
Share learning objectives
• Find out how heat travelsthrough space.
• Be able to explain ‘evaporation’using a particle model. (Sc1)
Problem solving
Discuss with pupilswhat is betweenus and the Sunand how heatenergy from theSun reaches us.
Capture interest (1)
Show two temperatureprobes in two equalvolumes of warm water, onein a narrow container, orconical flask, one in anopen, flat dish.
Capture interest (2)
Show pupils Crooke’sradiometer and explain whythe vanes move round.
Suggested alternative plenary activities (5–10 minutes)
Review learning
Wordsearch and definitionsfrom unit.
Sharing responses
Whole-class discussion ofActivity I7a.
Group feedback
In groups, use observationsfrom Activity I7b to debatewhether heaters should allbe painted black.
Word game
Match up the beginningsand endings of sentencesabout evaporation andradiation.
Looking back
Pupils revise andconsolidate knowledge fromthe unit.
Suggested alternative main activitiesActivity
Textbook I7
Activity I7a ICT
Activity I7b Practical
Activity I7c Paper
Activity I7c Catalyst InteractivePresentations 2
Learningobjectivesee above
i, ii and iii
i
i
Description
Teacher-led explanation and questioning OR Students workindividually, in pairs or in small groups through the in-text questionsand then onto the end-of-spread questions if time allows.
Cooling by evaporation Pupils use ICT to monitor liquids cooling byevaporation.
Radiation Pupils watch a demo of how silver and black surfaces areaffected by radiation.
The vacuum flask Optional demo followed by worksheet on thethermos flask.
Support animation of time-lapse pictures of puddle of waterevaporating; then child coming out of swimming pool/sea andshivering in breeze as water evaporates.
Approx. timing
20 min
20 min
5 min
10 min
5 min
Target group
C H E S
R/G G R S
✔ (✔ )
✔
✔
Learning outcomes
Most pupils will …
• recognise situation where cooling isoccurring by evaporation and relatethis to the difference between themovement of particles in a liquid anda gas
• recognise thermal energy transfer byradiation
• know that radiation does not requireparticles.
Some pupils, making less progress will …
• recognise common situation where evaporationcauses cooling
• recognise common situations where heating orcooling is caused by radiation
• know that radiation can happen across emptyspace.
Some pupils, making more progress will …
• also explain cooling by evaporation in terms of theloss of the particles carrying the most energy
Learning objectivesi Think about situations in which two input variables both influence the outcome variable. The structure of this lesson is based around the CASE approach. The starter activities give concrete preparation. The main activities move away from theconcrete towards a challenging situation, where pupils need to think. The extended plenary gives pupils time to discuss what they have learnt, tonegotiate a method to commit to paper and express their ideas verbally to the rest of the class.
Scientific enquiryii Use models to interpret results (green). (Framework YTO Sc1 8a)iii Use calculations to process data and make predictions (red). (Framework YTO Sc1 7b, 8d)
Suggested alternative starter activities (5–10 minutes)
Bridging the unit
Show pupils a cup of hot liquidand ask them to list four waysthat heat energy is lost from theliquid.
Setting the context
Set up a joulemeter, metal block, heater andthermometer as described in the textbook. Ask pupils toidentify input (independent) variable, outcome(dependent) variable, what happens to heat from theheater.
Concrete preparation
Show pupils a hot drink with a temperature probeproducing a cooling curve and ask how we could stop it from cooling.
Suggested main activitiesActivity
Textbook I8
Activity I8a Paper
Learningobjectivesee above
i, ii and iii
i
Description
Teacher-led explanation and questioning OR pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
What affects how tea cools? Pupils analyse a graph of a cup of teacooling and explain what is happening.
Approx.timing
30 min
20 min
Target group
C H E S
R/G G R S
✔ (✔ )
Suggested alternative plenary activities (5–10 minutes)
Group feedback
Highlight the importance of identifying all the variables in aninvestigation and controlling some of them.
Bridging to other topics
Give pupils examples of other things that are affected by more than oneindependent variable and ask them to say what the variables are.
Learning outcomes
Most pupils will …
• interpret data in terms of two input variables • discuss alternative interpretation of results.
Some pupils, making less progress will …
• compare pairs of results to interpret data interms of a fair test.
Some pupils, making more progress will …
• use their knowledge of temperature anddensity to interpret data
• begin to understand compensation – theinteraction of different values of two inputvariables to produce the same outcome.
Introduce the unit ● Either draw the outline of the unit map on the board then
ask pupils to give you words to add, saying where to addthem. Suggest some words yourself when necessary to keeppupils on the right track.
● Or give out the unit map and ask pupils to work in groupsdeciding how to add the listed words to the diagram. Thengo through it on the board as each group gives suggestions.
Share learning objectives● Ask pupils to write a list of FAQs they would put on a
website telling people about temperature. Collectsuggestions as a whole-class activity, steering pupilstowards those related to the objectives. Conclude byhighlighting the questions you want them to be able toanswer at the end of the lesson.
Problem solving● To demonstrate the need for thermometers with a common
scale, set up three bowls of water and ask for two pupilvolunteers. Explain that one bowl contains hot water andone contains cold water, and the third is an unknowntemperature. Ask one pupil to put a hand in the hot waterwhile the other puts a hand in the cold water. Time themfor one minute.
● Then ask them both to plunge their hands in the mysterybowl and say how it feels. Their answers should conflictand can be used to show that a hand is not a reliable gaugeof temperature, a thermometer is needed.
Capture interest (1)● Show different thermometers, e.g. liquid crystal for room
temperature or body temperature, maximum andminimum, clinical, etc., or if these are not available usephotos on Catalyst Interactive Presentations, and ask them totell you what thermometers are used for, and to name theplaces that they have seen different kinds of thermometers.
Capture interest (2)● Show video clips of different scenarios relating to heating
and cooling.
● Ask pupils to write down one thing they see that they havenever seen before or that they don’t understand in terms ofheating and cooling. Explain that they will find theexplanations for these scenarios in the coming unit.
➔ Unit map
Equipmentthree bowls of water – one hot at 45°C,one cold at 10°C and one mystery oneat 30°C
Suggested alternative starter activities (5–10 minutes)
Introduce the unit
Unit map for Heatingand cooling.
Share learning objectives
• Find out why we needthermometers.
• Be able to use different kindsof thermometers. (Sc1)
Problem solving
Use feeling in hands todecide how hot a bowl ofwater is to demonstrate theneed for a standard scale.
Capture interest (1)
Show different thermometers,discuss their uses. Or usephotos. Catalyst InteractivePresentations 2
Capture interest (2)
Show video clips of differentscenarios relating to heatingand cooling. Catalyst InteractivePresentations 2
I-Starters.qxd 12-Nov-03 8:39 AM Page 1
I2 StartersTemperature and energy
Recap last lesson● Using the pupil sheet, pupils match up types of thermometers
with their use.
Share learning objectives● Ask pupils to write a list of FAQs they would put on a website
telling people about temperature and energy. Collectsuggestions as a whole-class activity, steering pupils towardsthose related to the objectives. Conclude by highlighting thequestions you want them to be able to answer at the end ofthe lesson.
Problem solving● Pupils work in pairs to discuss the questions on the pupil
sheet (or it could be projected as an OHT).
● Ask pupils to volunteer answers and lead a discussion tointroduce the idea that temperature and energy are differentthings.
Capture interest (1)● Two pupil volunteers burn similar sized crisps or other food
snack under boiling tubes of water, clamped withthermometers inside. One is half full and one is nearly full ofwater. Note the temperature at the start, ask pupils to predictthe final temperature.
● Discuss the fact that there are similar amounts of energy but atthe end the water has risen to two different temperatures.Discuss the variables in the experiment and which one wascontrolled.
Capture interest (2)● Demonstrate the heating of two tubes of water with the same
volumes of water; heated with Bunsen burners, one with thehole open and one with the hole closed. Note the temperatureat the start, ask pupils to predict the final temperature.Measure the temperature rise in each with thermometers.
● Discuss the fact that the volumes of water were the same butdifferent amounts of energy were put in, resulting in differenttemperature rises. Discuss the variables in the experiment andwhich one was controlled.
➔ Pupil sheet
➔ Pupil sheet
Equipmenttwo boiling tubes, crisps, two retortstands with two clamps on each (onefor thermometer, one for boilingtube), two thermometers, tongs,heatproof mats, one Bunsen burnerto set fire to food
Equipmenttwo boiling tubes, two clamps, twothermometers, two Bunsen burners
Ordinary laboratory thermometer (range from –5°C to 110°C)
Clinical thermometer or plasticthermometer strip
High-temperature probe anddatalogger
Temperature probe anddatalogger
Alcohol thermometer (range from−80°C to 100°C)
To measure and record the temperature of a greenhouse over 24 hours
To measure and record the temperature ofa pottery kiln (several hundred degrees)
To measure the boiling point of carbondioxide (−78°C)
To measure the temperature when saltwater boils (about 105°C)
To measure the temperature of a person who is ill
I-Starters.qxd 12-Nov-03 8:39 AM Page 3
I2 StartersTemperature and energy
Problem solving
● Which of these, bath of water or kettle of water, is likely to be atthe higher temperature?
● Which of these contains the most heat energy?● Which would use the most fuel to heat?● Which would cost the most to heat?● Which would take longest to warm up?
● Which of these, bath of water or kettle of water, is likely to be atthe higher temperature?
● Which of these contains the most heat energy?● Which would use the most fuel to heat?● Which would cost the most to heat?● Which would take longest to warm up?
Explain your answers.
I-Starters.qxd 12-Nov-03 8:39 AM Page 4
I3 StartersBigger and smaller
Recap last lesson● Ask pupils to volunteer to complete the sentence read out to the
class, or the whole class does this on individual white boards.
Share learning objectives● Ask pupils to write a list of FAQs they would put on a website
telling people about expansion and contraction. Collectsuggestions as a whole-class activity, steering pupils towardsthose related to the objectives. Conclude by highlighting thequestions you want them to be able to answer at the end of thelesson.
Brainstorming● Ask pupils to work in groups and brainstorm some examples
they have come across of things expanding or contracting whenthe temperature changes and whether this is useful or anuisance.
● Then ask for groups to suggest some examples to share with theclass and write them up on the board. Explain that they willdiscover the reason for expansion and contraction in the lesson.
Problem solving● Shows pupils a bottle with a screw-on lid, and act as if it is too
tight to undo.
● Ask pupils for suggestions of methods to open the bottle.
● Put the top of the bottle into hot water so that the cap expands,then (with cloth if cap is hot) unscrew it easily.
● Explain that the metal top expands more than the glass bottlewhen it gets hot.
Capture interest● Demonstrate holding a bimetallic strip in a Bunsen flame and
ask why it curls. Explain that one metal expands more than theother.
Questions
Temperature is measured in …
Energy is measured in …
When something is heated theparticles get more …
To measure the heat energy used I could use a …
To measure the temperature I could use a …
A big jug of water has more energythan a small one at the sametemperature because…
Examplesliquid in thermometers, hands andfeet swelling in hot weather;balloons going down when it iscool; telephone and electric wiressagging in hot weather; doorssticking; air inside bike tyres; bottletops in hot water
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Pupils complete thesentences read out tothem about temperatureand energy.
Share learning objectives
• Find out what happens whensomething is heated or cooled.
• Describe some examples ofheating causing expansion.
• Use the particle model to explainheating and cooling. (Sc1)
Brainstorming
Pupils suggest examples oftimes and places where thingsexpand or contract when thetemperature changes.
Problem solving
Demo how a tight screwcap can be taken off abottle.
Capture interest
Demo the heating ofa bimetallic strip.
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I4 StartersAll change
Examplesliquid in thermometer,metal bar, railway lines,motorway sections, pipes,cables, planes whenflying, furniture/housesduring the day, twometals in a bimetallicstrip
➔ Pupil sheet
Equipmentbeaker full of water andice cubes, thermometerclamped in it, stirringrod, or datalogger withtemperature probe andgraph displayed
Recap last lesson● Ask pupils for five examples of things that expand when they are heated
or contract when cooled, prompting pupils to be as specific as possible.
Share learning objectives● Display the objectives for pupils, explain what ‘changes of state’ means
and review vocabulary for these changes.● Explain that pupils will see some changes of state in the activities they do.● Remind pupils that they will need to make careful observations and then
be able to use their new knowledge to explain what they saw.
Problem solving● Ask pupils to describe what information they can get from the graph.● They should suggest that – it’s a cooling curve, the substance used is gold,
the experiment lasted 20 minutes, the temperature range was from 800°Cto 1500°C.
● Then point out that there’s an unexpected flat part in the graph. A fewpupils might suggest that the gold is solidifying – but don’t tell them if noone thinks of this. Suggest that in the lesson they will look at a substancecooling and learn why the graph is this shape.
Capture interest (1)● Show a ‘drink’ with ice cubes, with thermometer clamped in it – or better,
a probe with temperature displayed – ideally as a graph.● Ask pupils to predict how long the temperature will stay constant. They
can write down their prediction. The experiment can be left runningthroughout the lesson; pupils and teacher can check on it occasionallyand pupils can check at the end to see if their prediction was correct.
● Although simple theory says the temperature should be 0°C, it may beslightly above this. The water next to the ice cube will be at 0°C, but thereis a temperature gradient to the glass, and from the glass to the air in theroom. Stirring will help. The temperature should remain constant untilthe ice has completely melted.
Capture interest (2)● Pupils are asked to give opposites for the following words: melt and
condense (opposite of melt = freeze or solidify, opposite of condense = boilor evaporate).
● Pupils are asked to explain the difference between melt and dissolve.(Melt is just one substance changing state, dissolve is a solute being mixedwith a solvent.)
● Demonstrate dissolving sugar in water, and contrast it with melting sugar(on a tin lid on a triangle on a tripod over a Bunsen burner).
Graph to show temperature of gold metal after heating to 1500 °C and then allowing it to cool
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I5 StartersConduction
Recap last lesson● Play ‘It’s on the tip of my tongue’ by giving definitions and
asking pupils to suggest what word you are trying to say. Eitherchoose volunteers to answer, or use individual whiteboards tojudge whole class recall of the last lesson.
Share learning objectives● Display the objectives for pupils and ask pupils to describe the
particle arrangements in solids, liquids and gases.● Explain that conduction needs particles to pass on energy. Ask
pupils to suggest in which state things will be the bestconductors and explain why they think that.
● Ask pupils what conductors and insulators are to gauge theirprior knowledge from Key Stage 2.
Problem solving● Show some examples of saucepans that have metal pans and
wooden or plastic handles.● Ask pupils to suggest why the various materials are used and
what their properties are.● Sum up by saying that in the lesson they will learn how the
particle model can explain these properties.
Capture interest (1)● To demonstrate this, wedge ice in the bottom of a Pyrex test
tube with gauze. Fill it up with water. Heat the top of the waterwith a Bunsen burner on a medium flame, holding the test tubeat an angle. (Care! if dry glass is heated it will crack.)
● The water at the top boils while the ice is unmelted. This isbecause water is a bad conductor, and convection can only carryheat energy upwards.
Capture interest (2)● Set up two beakers of very hot water (60–70°C).● Two volunteers stir one spoonful of sugar into each beaker, one
with a plastic spoon and one with a metal spoon.● Ask the class to predict what the volunteers will feel; the
volunteers report back.● Theory says that metal is a better conductor, so the volunteer
stirring the sugar with the metal teaspoon will feel the spoongetting hot sooner.
● Introduce the terms thermal conductor and thermal insulator.
ExamplesWhen something turns from solidto liquid meltingThe opposite of melting freezingWhen something turns from gas toliquid condensingThe temperature when a liquidturns to a gas boiling pointWhen a liquid is freezing thetemperature stays constant
Equipmenta selection of saucepans withwooden or plastic handles orphotographs of them (e.g. fromcatalogues)
EquipmentPyrex test tube, crushed ice (to fitin test tube), gauze, Bunsen burner,test tube holder
Equipmenttwo beakers, kettle, plastic andmetal teaspoons, small beaker ofsugar
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Play ‘It’s on the tipof my tongue’ withwords for changes ofstate.
Share learning objectives
• Find out about conduction.• Use the particle model to
explain conduction.• Describe materials as
conductors or insulators.
Problem solving
Show pupils someexamples of saucepans andask them to suggest whythey have metal pans andwooden or plastic handles.
Capture interest (1)
Demo ice trapped by gauzeat the bottom of a testtube with a Bunsen burnerheating the water at thetop to boiling point.
Capture interest (2)
Volunteer pupils stir sugar intobeakers of very hot water, one with aplastic spoon and one with a metalspoon. The class predicts what thevolunteers will feel.
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I6 StartersConvection
Recap last lesson● Ask pupils to tell you three things about Activity I5a from the last lesson.● Collect three suggestions from one pupil, ask who has anything different
to build up full account on the board.
Share learning objectives● Explain the word fluid (can flow, so can be gas or liquid – need to explain
that a gas can flow).● Remind pupils that gases are bad conductors (and that heat energy cannot
flow downwards in water – if they saw the demonstration in I5).● Remind pupils that scientists need to be able to use scientific theory to
explain observations.
Problem solving● Show pupils the diagram on the pupil sheet of the heating element at the
bottom of the kettle, and the cooling compartment at the top of the fridge.● To illustrate, if possible, have a real kettle to show.● The pupil sheet asks the question: Why is the heating element at the
bottom of the kettle, but the cooler is at the top of the fridge?● If pupils say ‘because heat goes upwards’, ask them to suggest what they
think is happening in the fridge. If necessary, prompt them by saying thatif hot air rises, maybe cool air falls.
● Explain that they will discover the explanation in terms of the particlemodel in the lesson.
Capture interest (1)● Demonstrate the candle box to show how smoke moves in convection
currents.● Explain that the smoke is acting as a marker, to show the path of the air.● First hold the smoking string over the candle chimney, then over the
other chimney, where the smoke will be dragged down the chimney intothe box by the convection current.
● Explain that they will carry out an experiment themselves to see thishappening in liquids and discover the explanation in terms of particles inthe lesson.
Capture interest (2)● Show video clips of birds soaring on thermals and hang gliders circling up
and down on thermals.● Ask pupils to suggest how they are rising and falling without flapping
their wings and without engines.● Explain that they will discover the explanation in terms of the particle
model in the lesson.
➔ Pupil sheet
➔ Catalyst InteractivePresentations 2
➔ Pupil sheet
Equipmentbox with glass front andtwo glass chimneys,candle, string (twine), orwax straws that will burnwith a smoky flame,matches
You are going to see two demonstrations to show you how heatenergy moves in air and water.
Draw arrows on the diagram to show which way the smoke (and air) moves.
candle
B C
A D
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I7 StartersEvaporation, radiation
Recap last lesson● Suggest that some people say ‘heat always rises’ and ask pupils to give
some examples from the last lesson that fit that pattern.● Elicit from pupils what they think the situation is with cold air.● Then ask pupils if they think that is always the case and help them refine
the statement to ‘heat rises in liquids and gases’ because convection onlyhappens in liquids and gases.
Share learning objectives● Ask pupils to write a list of FAQs they would put on a website telling
people about evaporation and radiation. Collect suggestions as awhole-class activity, steering pupils towards those related to theobjectives. Conclude by highlighting the questions you want them to beable to answer at the end of the lesson.
Problem solving● Ask pupils to give the names of the ways that heat can travel and to
describe how these ways work.● Pupils will name conduction and convection, and their descriptions
should show that each needs a material medium.● Ask pupils what is between us and the Sun and elicit the idea that ‘space’
or a ‘vacuum’ means absence of particles.● Conclude that there must be another method for heat transfer since heat
reaches us from the Sun, and explain that they will learn about this in thelesson.
Capture interest (1)● Set up two temperature probes in two equal volumes of warm water with
equal initial temperature, one in a narrow container or conical flask, onein an open, flat dish.
● Project datalogging graphs to show the temperatures over time.● Ask pupils to suggest why there is a difference in the cooling curves.
Capture interest (2)● Show pupils a Crooke’s radiometer (sold as toys: an evacuated bulb,
balanced inside is a mill with vanes that have white and black sides).
● In sunlight the mill spins fast. The reason is that the black surfaceabsorbs more heat energy, it warms up the gas on that side of the vane,the gas particles move faster on the black side, they hit the vane andmake it spin.
Equipmenttwo containers of warmwater (one in a conicalflask, one in a wide, flatdish), two temperatureprobes and dataloggingequipment
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Ask pupils to give someexamples of heat risingfrom the last lesson.
Share learning objectives
• Find out how heat travelsthrough space.
• Be able to explain‘evaporation’ using a particlemodel. (Sc1)
Problem solving
Discuss with pupils what isbetween us and the Sun andhow heat energy from the Sunreaches us.
Capture interest (1)
Show two temperature probesin two equal volumes ofwarm water, one in a narrowcontainer, or conical flask,one in an open, flat dish.
Capture interest (2)
Show pupils Crooke’sradiometer and explainwhy the vanes moveround.
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I8 StartersExplaining the results – Thinkabout
Bridging to the unit● Show pupils a cup of a hot drink and ask them to list the four
ways the drink loses heat energy.
● Pupils respond (hopefully) with conduction, convection,radiation and evaporation.
● If pupils say where the heat is lost, e.g. through the sides, thenprompt them to give the name, e.g. ‘What do we call it whenheat travels through a solid like the side of the cup?’
Setting the context● Set up a metal block, heater, joulemeter and thermometer.
● Ask pupils to identify the independent variables and what wecan do to control each one. (Type of metal, mass of block,insulation or not around block, power of heater, time thatexperiment runs for.)
● Ask pupils to identify the dependent variable (temperature).
Concrete preparation● Set up a large mug of hot liquid with a temperature probe inside
it, and a cooling curve displayed on screen.
● Ask pupils to suggest what shape the graph will be if the liquidcools more slowly or more quickly.
● Then ask pupils what we could change so that the graph goesdown faster/more slowly.
● Remind pupils that these ideas are independent or inputvariables.
Equipmentmetal block, heater, joulemeter,thermometer, heatproof mat, powersupply for heater
Answerslid/no lid, amount of liquid,starting temperature, roomtemperature, size of mug, materialof mug, wrapping around mug,colour of mug
Suggested alternative starter activities (5–10 minutes)
Bridging to the unit
Show pupils a cup of hot liquid andask them to list four ways that heatenergy is lost from the liquid.
Setting the context
Set up a joulemeter, metal block, heater and thermometeras described in the textbook. Ask pupils to identify input(independent) variable, outcome (dependent) variable,what happens to heat from the heater.
Concrete preparation
Show pupils a hot drink with a temperatureprobe producing a cooling curve and ask how wecould stop it from cooling.
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I1aTeacher
activity notesMaking a thermometer
Running the activityPupils work in pairs to produce a simple water thermometer, calibrate it and use itto measure some different temperatures.
Core: Full instructions are given on the sheet.
Extension: Pupils design their own thermometers from equipment provided.
Expected outcomesPupils discover that the water appears to move up the tube as it gets hotter anddown the tube as it gets colder. They should link this to expansion andcontraction of the water.
PitfallsPupils may need assistance in getting the initial level of the water correct. It needsto be about halfway up the glass tube.
Calibrating to 0°C using iced water will, of course, not be very accurate becausewater expands as it cools between +4° and 0°C.
Safety notesTake care pupils do not break the thin glass tubes.
AnswersCore:1 Moved down the tube.
2 Moved up the tube.
3 Depends on results (should be around 37°C).
4 Pupils should describe the process similar to step 6 on the Core sheet.
5 Test it at different temperatures with a clinical thermometer or a digitalthermometer to see if you get the same answers.
Extension:1 Colder – level went down; hotter – level went up.
2 Depends on results (should be around 37°C).
3 Test it at different temperatures with a clinical thermometer or a digitalthermometer to see if you get the same answers.
4 Depends on the thermometer.
5 Water would evaporate out of the tube, making the thermometer inaccurate.
6 The liquid level moves faster, they are more accurately calibrated, they stayaccurate with time, the liquid in them freezes at a lower temperature and boilsat a higher temperature so they can be used over a wider range of temperatures.
Type Purpose DifferentiationPractical Pupils make a simple water thermometer and observe expansion and contraction of
liquid as the temperature changes.Core, Extension
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I1aTechnician
activity notesMaking a thermometer
EquipmentFor each pair:
● boiling tube● boiling tube rack● bung with 10 cm glass tube● access to water bath at 50 °C● beaker of iced water● two sticky labels● coloured water (food dye will do)● marker pen (waterproof)
For your informationRunning the activityPupils work in pairs to produce a simple water thermometer, calibrate itand use it to measure some different temperatures.
Core: Full instructions are given on the sheet.
Extension: Pupils design their own thermometers from equipment provided.
Expected outcomesPupils discover that the water appears to move up the tube as it gets hotter anddown the tube as it gets colder. They should link this to expansion andcontraction of the water.
PitfallsPupils may need assistance in getting the initial level of the water correct. It needsto be about halfway up the glass tube.
Calibrating to 0°C using iced water will, of course, not be very accurate becausewater expands as it cools between +4° and 0°C.
Safety notesTake care pupils do not break the thin glass tubes.
Type Purpose DifferentiationPractical Pupils make a simple water thermometer and observe expansion and contraction of
liquid as the temperature changes.Core, Extension
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I1aActivity
CoreMaking a thermometer
A thermometer is made from a very thin tube of glass filled with a liquid like mercury. In this activity you are going to make a verysimple water thermometer.
Equipment● boiling tube ● bung with glass tube● boiling tube rack ● coloured water● water bath at 50ºC ● beaker of iced water● marker pen ● sticky labels
Obtaining evidence1 Fill the boiling tube almost to the top with the coloured water.2 Fit the bung and glass tube into the boiling tube as shown. If the
water comes out of the top of the glass tube, take the bung off,tip some water out and try again.
3 Adjust the water level so it is about halfway up the glass tube.4 Place the boiling tube into the beaker of iced water. When the
water in the glass tube stops moving, mark this new water level 0ºC.5 Place the boiling tube in the water bath. When the water in the glass tube
stops moving, mark this new water level 50ºC.6 Measure the distance between the 0ºC and the 50ºC marks. Divide this
distance by 10. Use your answer to mark 5ºC intervals along yourthermometer (i.e. 5ºC, 10ºC, 15ºC and so on up to 45ºC). You have nowcalibrated your thermometer.
7 Hold the boiling tube tightly between both your hands. When the water inthe glass tube stops moving, measure the water level against the marks onyour thermometer. Record the temperature.
8 Take further measurements, such as:● on a sunny windowsill or above a radiator● in a cool cupboard or outside on a cold day.
9 Make a table to record your results.
Considering the evidence
1 How did the water level change when your thermometer got cold?2 How did the water level change when your thermometer got hot?3 From your results, what is your body temperature?4 Describe the method for putting a scale on your thermometer.
Evaluating
5 How accurate do you think your water thermometer is? How could youtest this?
A thermometer is made from a very thin tube of glass filled witha liquid like mercury. In this activity you are going to make a verysimple water thermometer.
Equipment
● boiling tube● boiling tube rack● water bath at 50ºC● marker pen● bung with glass tube● coloured water● beaker of iced water● sticky labels
Obtaining evidence
1 Using the equipment available, design a water thermometer thatwill measure temperatures between 0ºC and 50ºC.
2 Calibrate your thermometer in 5ºC intervals.3 Use your thermometer to record various temperatures, for
example:● your body (hold the thermometer in your hands)● a sunny windowsill● a cool cupboard● in the main part of the fridge.
Considering the evidence
1 What happened to the water level as your thermometer gothotter and colder?
2 From your results, what is your body temperature?
Evaluating
3 How accurate is your thermometer? How could you test this?4 How quickly does your thermometer reach the new temperature
when you move it to a different place?5 What would happen if you left your thermometer for a few days?6 What are the advantages of the liquid-filled thermometers you
Running the activityPupils heat different volumes of water electrically so that the temperature rises by 10°C. Theymeasure the amount of energy needed using a joulemeter. The activity sheet directs the pupilsto find out how the joulemeter works before starting the experiment. This is becausejoulemeters vary greatly. Electrical heaters also vary. Try to select beakers or other containersthat ensure that the bulk of the heater is under water.
Core: Pupils follow the instructions on the sheet.
Help: Pupils record their measurements and answers on the sheet.
Extension: The sheet leads pupils through calculating energy efficiency.
Other relevant materialSkill sheet 16: Energy transfer diagrams
Expected outcomesMore energy will be needed to raise the temperature of larger volumes of water. Theoretically,twice the volume of water should require twice the energy, but energy losses to thesurroundings may be different if different amounts of the heater are under water.
PitfallsEnsure that the pupils understand how to use the joulemeter. Make sure that they set the powerpacks to the correct voltage for the heater. Make sure that the heater will not overbalance thebeaker. Clamp it if necessary.
Safety notesWarn pupils that the heater will become very hot. Have a heatproof mat on which to rest theheater when not in use. Turn off the power supply between experiments. Warn againsthandling switches and sockets with wet hands.
AnswersCore:1 –(thermal energy)→ water –(thermal energy)→ thermometer 2 Depends on individualresults. 3 There are more particles in 200cm3 of water than 100cm3 of water, so more energyis needed to increase the kinetic energy of all the particles. 4 The average energy per particlewas increased by the same amount, so the same temperature rise occurred, but there were moreparticles in 200cm3 water than in 100cm3 water, so more energy was needed.
Help:1 –(thermal energy)→ water –(thermal energy)→ thermometer 2 Depends on individualresults. 3 Particles, 200, 100, energy, 200, temperature.
Extension:1 Pupils should predict that 200 cm3 takes more energy because it contains more particles. 2 See Core question 1. 4 – 5 See Core questions 3 and 4. 6 Pupils should find it takesapproximately double the energy but may identify that some heat is transferred to thesurroundings. 7 a 4.2 × 100 = 420 J b 4.2 × 100 × 10 = 4200 J 8 4200 × 2 = 8400 J 9 Answer should be no; some energy is lost to the surroundings, but this will depend on pupildata. 10 Some of the energy is lost to the surroundings.
Type Purpose DifferentiationPractical To show pupils that different amounts of energy can cause the same rise in temperature,
i.e. that temperature and energy are related but not the same.Core, Help, Extension
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I2aTechnician
activity notesEnergy and temperature
Other relevant materialSkill sheet 16: Energy transfer diagrams
EquipmentFor each group:
● joulemeter● power supply● heating element● three leads● thermometer● two clamp stands with clamps and bosses● 250 cm3 beaker● 150 cm3 beaker● 100 cm3 measuring cylinder
For your informationRunning the activityPupils heat different volumes of water electrically so that the temperature rises by10 °C. They measure the amount of energy needed using a joulemeter. The activitysheet directs the pupils to find out how the joulemeter works before starting theexperiment. This is because joulemeters vary greatly. Electrical heaters also vary.Try to select beakers or other containers that ensure that the bulk of the heater isunder water.
Core: Pupils follow the instructions on the sheet.
Help: Pupils record their measurements and answers on the sheet.
Extension: The sheet leads pupils through calculating energy efficiency.
Expected outcomesMore energy will be needed to raise the temperature of larger volumes of water.Theoretically, twice the volume of water should require twice the energy, butenergy losses to the surroundings may be different if different amounts of theheater are under water.
PitfallsEnsure that the pupils understand how to use the joulemeter. Make sure that theyset the power packs to the correct voltage for the heater. Make sure that the heaterwill not overbalance the beaker. Clamp it if necessary.
Safety notesWarn pupils that the heater will become very hot. Have a heatproof mat on whichto rest the heater when not in use. Turn off the power supply betweenexperiments. Warn pupils not to handle switches and sockets with wet hands.
The heater gets very hot.Put it on a heatproof matbetween experiments anddon’t touch the hot part.
Switch off the power supplybetween experiments.
– +
joulemeter
heater
thermometer
power supplywater
water thermometer.......................
energy
.......................
energy
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I2aActivity
HelpEnergy and temperature
You are going to find out how much energy is needed to heat100cm3 and 200cm3 of water by 10°C.
Do you know how to use the joulemeter? If not, ask your teacher.
Do you know the correct voltage for your heater? If not, ask yourteacher.
Obtaining evidence
1 Set up the apparatus as shown in the diagram.2 Ask your teacher to check your apparatus.3 Measure 100cm3 of water into the beaker. Use a measuring cylinder.
4 Record the temperature in the table.
5 Work out the end temperature. This is the starting temperature + 10°C.Write the end temperature in the table.
6 Heat by 10°C. Stir the water all the time. Write down the energytransferred.
The heater gets very hot.Put it on a heatproof matbetween experiments anddon’t touch the hot part.
Switch off the power supplybetween experiments.
– +
joulemeter
heater
thermometer
power supplywater
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I3aTeacher
activity notesExpansion in solids
Running the activityThe teacher demonstrates the experiments. Pupils complete the sheets as they watch.
The ball and ring: Show that the ball will fit through the ring, but when the ball isheated in a Bunsen flame it will not fit because it has expanded. If the ring is thenheated as well it too expands, so the ball will fit through. If both are put in cold waterthey will both contract, so the ball will fit through the ring.
The metal rod: Set up the experiment as shown on the sheet, with the metal rod restinggently on the pin with the paper flag. Heat the metal rod carefully by holding aBunsen over it. (Taking care not to set the paper flag on fire!) As the rod expands itwill roll the pin, and the flag will turn.
Other relevant materialIf the equipment is available, the breaking barexperiment could also be demonstrated here. As thelong metal bar is heated the screw is tightened. When it cools, the long metal bar contracts, breakingthe cast iron bar.
Expected outcomesPupils understand the principles behind expansion andcontraction in solids, in terms of particles movingapart and closer together.
PitfallsMovement of the paper flag can be difficult to observe, especially from a distance.
Safety notesDo not let pupils handle hot metal objects.
Use tongs or a heatproof glove to hold the hot chain.
Do not set fire to the paper flag.
Use a safety screen (and goggles for the teacher) for the breaking bar demonstration.
Answers1 yes 2 no 3 The ball has been heated. Its particles vibrate more and take upmore space. The ball expands. 4 The ball fits through again. 5 The ring has beenheated. Its particles vibrate more and take up more space. The ring expands and theball can fit through. 6 yes 7 The ball and ring have been cooled down. Theirparticles vibrate less and take up less space. They both contract. 8 The flag rotates.9 The flag rotates because the pin is rotating, so the rod must be expanding androlling the pin along the bench. 10 The rod has been heated. Its particles vibratemore and take up more space. The rod expands, rolling the pin. 11 The flag willmove back to where it started because the rod will cool and contract.
Type Purpose DifferentiationPractical Demonstrate expansion and contraction while pupils observe and complete an activity
sheet.Core
heat screw tightenedas bar is heated
cast iron bar fitsthrough hole
strong metal holder long metal bar
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I3aTechnician
activity notesExpansion in solids
Other relevant material If the equipment is available, the breaking bar experiment could also be demonstrated here. As the long metalbar is heated the screw is tightened. When it cools, the long metal bar contracts, breaking the cast iron bar.
EquipmentFor teacher demonstrations:
● metal ball and ring● Bunsen burner● tongs or heatproof glove● heatproof mat● metal rod at least 30 cm long● stand and clamp● metal pin with paper flag attached
For your informationRunning the activityThe teacher demonstrates the experiments. Pupils complete the sheets as they watch.
The ball and ring: Show that the ball will fit through the ring, but when the ball is heated in a Bunsen flameit will not fit because it has expanded. If the ring is then heated as well it too expands, so the ball will fitthrough. If both are put in cold water they will both contract, so the ball will fit through the ring.
The metal rod: Set up the experiment as shown on the sheet, with the metal rod resting gently on the pinwith the paper flag. Heat the metal rod carefully by holding a Bunsen over it. (Taking care not to set thepaper flag on fire!) As the rod expands it will roll the pin, and the flag will turn.
Expected outcomesPupils understand the principles behind expansion and contraction in solids, in terms of particles movingapart and closer together.
PitfallsMovement of the paper flag can be difficult to observe, especially from a distance.
Safety notesDo not let pupils handle hot metal objects.
Use tongs or a heatproof glove to hold the hot chain.
Do not set fire to the paper flag.
Use a safety screen (and goggles for the teacher) for the breaking bar demonstration.
Type Purpose DifferentiationPractical Demonstrate expansion and contraction while pupils observe and complete an activity
sheet.Core
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I3aActivity
CoreExpansion in solids
When a solid is heated it expands. Your teacher will demonstratesome experiments to show this. Observe these experimentsclosely and answer these questions.
Experiment 1: The ball and ring
1 Observe the ball and ring.
1 Can the ball fit through the ring?
2 The ball is now heated in a Bunsen flame.
2 Can the ball fit through the ring now?3 Explain why this happens. Use the word ‘particles’
in your answer.
3 The ring is now heated in a Bunsen flame.
4 Describe what happens.5 Explain why this happens. Use the word ‘particles’ in your
answer.
4 The ball and ring are both put into cold water.
6 Can the ball fit through the ring?7 Explain why this happens. Use the word ‘particles’ in your
answer.
Experiment 2: The metal rod
5 The metal rod is held firmly at one end. Therod is heated up. Observe the rod carefully.
8 What happens to the flag on the pin?9 What does this show?10 Explain why this happens. Use the word
‘particles’ in your answer.11 What do you think will happen to the flag
Running the activitySet up the flask and capillary tube as described in the Technician activity notes.Place the flask in different temperatures of water and measure the level of the aircolumn against the scale on the ruler.
Pupils record the results in a table, plot a graph and answer questions about whatthey have observed.
Expected outcomesPupils should discover a relationship between temperature and volume.
Safety notesThe capillary tube is fragile – handle with care.
ICT opportunitiesA spreadsheet can be used to produce a graph of the results.
Answers1 Depends on results.
2 Depends on results.
3 Volume increases with temperature.
4 As the temperature increases, the air particles move further apart from eachother.
5 a Diagram shows particles further apart.b Diagram shows particles closer together.
Type Purpose DifferentiationPractical Demonstration that air expands and contracts with temperature. Core
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I3bTechnician
activity notesExpansion in gases
EquipmentFor teacher demonstration:
● round-bottomed flask● bung with 50 cm capillary tube● 30 cm ruler● sticky tape● stand and clamp● large beaker● coloured water (food dye will do)● kettle● ice● thermometer
When setting up the apparatus, first suck up a small amount of coloured liquid toseal the capillary tube about halfway up its length. Pupils will measure the bottomend of this ‘slug’ of coloured water against the scale on the ruler.
For your informationRunning the activitySet up the flask and capillary tube as described above. Place theflask in water at different temperatures and measure the level ofthe air column against the scale on the ruler.
Pupils record the results in a table, plot a graph and answerquestions about what they have observed.
Expected outcomesPupils should discover a relationship between temperature andvolume.
Safety notesThe capillary tube is fragile – handle with care.
Type Purpose DifferentiationPractical Demonstration that air expands and contracts with temperature. Core
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I3bActivity
CoreExpansion in gases
In this experiment you are going to observe whathappens to the size of a column of air at differenttemperatures.
Your teacher will demonstrate this experiment to you.The slug of water will move as the air inside the flaskexpands and contracts.
Your teacher will measure the height of the bottom ofthe slug of water as the flask is placed in water atdifferent temperatures.
1 Copy and complete this table.
2 Use the results in your table to draw a line graph ofheight of water against temperature. The height ofthe water slug shows how the volume of air in theflask changes.
1 At what temperature is the volume of air thesmallest?
2 At what temperature is the volume of air the biggest?3 What conclusions can you make about the
relationship between the volume of the air and thetemperature?
4 Explain why there is this relationship.
3 The diagram on the right shows the molecules of air inside thecapillary tube at 50ºC.
5 Draw a similar diagram to show the molecules of air inside thecapillary tube at:a 75ºCb 25ºC
Running the activityThis is a paper activity for more able pupils, who have to record information fromthe sheet and answer questions.
Expected outcomesPupils understand that different liquids expand and contract by different amounts,but water does not behave as you would expect – its particles do not fit togethercompactly as it freezes, but form crystals which are less dense than water.
Answers1 They vibrate more and spread out.
2 Glycerol, oil, water, paraffin.
3 4°C
4 The particles vibrate less and fit closer together.
5 Instead of forming a close-fitting solid, the water particles form crystals whichfit together in a non-compact way, forming ice which is less dense than water.
6 It is above freezing point.
7 The water at the bottom is not frozen so they will not freeze either.
Type Purpose DifferentiationPaper Demonstration that air expands and contracts with temperature. Extension
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I3cActivity
ExtensionExpansion in liquids
Different liquids expand andcontract by different amounts. Youare going to investigate expansionof some liquids, and see how waterbehaves differently.
All of these glass bottles are the samesize. They were all filled to the samemark at the start of the experiment.
When hot water was added to thetrough, the liquid levels in the tubeschanged.
1 Use the scale shown to measure how much each liquid rose. Record this in a table.
1 Explain what happened to the particles in the liquids.2 List the four liquids in order of increasing amount of expansion.
Water contracts as it gets colderdown to a temperature of 4°C.From 4ºC down to 0°C it expands.Ice crystals start forming at +4°C.The crystals fit together in anon-compact way with spacebetween them. So, even though iceis a solid, it is less dense than liquidwater. This means that ice floats ontop of water.
3 Here are four bottles of water atdifferent temperatures. At whattemperature is the water the most dense?
4 Explain why liquids contract as they get colder.5 Explain why below 4ºC water does not behave as you would have expected.
2 Look at this diagram of a fish pond.
6 What does this tell you about thetemperature of the water below theice?
7 How do fish survive at the bottom offrozen ponds in winter?
Running the activityPupils work in small groups, or the activity could be carried out as a teacher demonstration. If limiteddatalogging apparatus is available then the experiment may be done as part of a circus of experiments. It isalso possible to carry out the activity using thermometers.
Core: The method is given and the pupils follow the instructions to produce their own graphs. Questionshelp them analyse the graph. They are asked to explain what is happening in terms of particles.
Help: The sheet provides a set of axes for pupils to record their results. More structured questions lead themto their conclusions. Instructions for the experiment are not given on this sheet, so pupils will need helpwith the activity (instructions on the Core sheet), or the Help sheet can be used to accompany a teacherdemonstration.
Extension: Pupils predict what they think will happen, then plan and carry out their own full investigation.
Other relevant materialIT Activities for Science 11–14 (Heinemann): Datalogging guides (p.165–7); spreadsheets ‘Melting moments’(p. 18–19) and ‘From ice to steam’ (p. 25–6).
Extension pupils could use the writing frames on: Skill sheet 20: Writing frame: Planning an investigation Skill sheet 21: Writing frame: Reporting an investigation
Expected outcomesThe graph produced by the cooling stearic acid should show a plateau. From this, pupils should be able todetermine the melting point of the stearic acid.
PitfallsThe timescale of the experiment should be at least 20 minutes. The stearic acid will need to be re-melted toallow for the removal of the temperature probes at the end of the experiment.
Safety notesStearic acid can be harmful. Wash hands after use. Take care with hot water. If scalded with hot stearic acidor water, hold the affected part under cold running water.
AnswersCore:1 Goes down steadily, levels out, then goes down again. 2 Depends on graph/ stearic acid used. 3 Depends on graph/ stearic acid used. 4 Particles of the liquid stearic acid are losing energy, they movemore slowly, forces of attraction form, they become particles of a solid.
Help:1 No (levelled out for a bit). 2 Depends on graph/ stearic acid. 3 Depends on graph/ stearic acid. 4 Liquid, solid, temperature, slowly, join, melting.
Extension:1 It will stay constant. 2 Energy is being released and used to make forces of attraction between themolecules. 3 Goes down steadily, levels out, then goes down again. 4 Depends on graph/ stearic acid.5 Depends on graph/ stearic acid. 6 Particles of the liquid stearic acid are losing energy, they move moreslowly, forces of attraction form, they become particles of a solid. 7 a Any valid method. b Datalogger –many more readings taken, easier to read than a thermometer to a greater level of accuracy. 8 Any validmethod involving re-melting the stearic acid and recording the temperature as it melts.
Type Purpose DifferentiationICT Pupils use temperature probe and datalogger to produce a cooling curve for stearic acid. Core, Help, Extension
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I4aTechnician
activity notesChanges of state
Other relevant materialIT Activities for Science 11–14 (Heinemann): Datalogging guides (p.165–7);spreadsheets ‘Melting moments’ (p.18–19) and ‘From ice to steam’ (p.25–6).
Extension pupils could use the writing frames on: Skill sheet 20: Writing frame: Planning an investigationSkill sheet 21: Writing frame: Reporting an investigation
Equipment neededFor each group (or teacher demonstration):
● Bunsen burner● boiling tube of stearic acid (or wax)● clamp stand● tripod and gauze● beaker of water● datalogger● temperature probe● computer and interface
For your informationRunning the activityPupils work in small groups, or the activity could be carried out as a teacherdemonstration. If limited datalogging apparatus is available then the experimentmay be done as part of a circus of experiments. It is also possible to carry out theactivity using thermometers.
Core: The method is given and the pupils follow the instructions to produce theirown graphs. Questions help them analyse the graph. They are asked to explainwhat is happening in terms of particles.
Help: The sheet provides a set of axes for pupils to record their results. Morestructured questions lead them to their conclusions. Instructions for theexperiment are not given on this sheet, so pupils will need help with the activity(instructions on the Core sheet), or the Help sheet can be used to accompany ateacher demonstration.
Extension: Pupils predict what they think will happen, then plan and carry outtheir own full investigation.
Expected outcomesThe graph produced by the cooling stearic acid should show a plateau. From this,pupils should be able to determine the melting point of the stearic acid.
PitfallsThe timescale of the experiment should be at least 20 minutes. The stearic acidwill need to be re-melted to allow for the removal of the temperature probes at theend of the experiment.
Safety notesStearic acid can be harmful. Wash hands after use. Take care with hot water. Ifscalded with hot stearic acid or water, hold the affected part under cold runningwater.
Type Purpose DifferentiationICT Pupils use temperature probe and datalogger to produce a cooling curve for stearic acid. Core, Help, Extension
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I4aActivity
CoreChanges of state
As a liquid cools, its particles move more slowly and it turns into a solid. You are going to look at the cooling curve for stearic acid as it changes state.
Equipment
● Bunsen burner● boiling tube of stearic acid● beaker of water● clamp stand● tripod and gauze● temperature probe● computer and interface● datalogging software
Obtaining evidence
1 Set up the computer and run thedatalogging software.
2 Set the timespan of the experimentto 20 minutes.
3 Place the boiling tube of stearic acid inthe beaker of water and heat it untilthe stearic acid melts. Remove it fromthe beaker still attached to the standand clamp.
4 Put the temperature probe into thestearic acid.
5 Remove the boiling tube from the hotwater and put it in the rack.
6 Start recording.7 Once the stearic acid is totally solid, stop recording.
Presenting the results
The computer will draw a graph of temperature against time.
8 Print out the graph, or draw a sketch of it.
Considering the evidence
1 Describe the shape of the graph.2 At what point did the temperature stop falling?3 Use the graph to work out the melting point of the stearic acid.4 Explain what is happening to the stearic acid particles at this point.
As a liquid cools, its particles move more slowly and it turns into a solid. You are going to look at the cooling curve for stearic acid as it changes state.
Equipment
● Bunsen burner● boiling tube of stearic acid● beaker of water● clamp stand● tripod and gauze● temperature probe● computer and interface● datalogging software
Planning and predicting
1 Predict what will happen to the temperature of the liquid at thepoint that it solidifies.
2 Explain why you think this.
1 Plan an investigation to prove your prediction. Ask your teacherto approve your plan.
Obtaining evidence
2 Carry out your investigation and display your results.
Considering the evidence
3 Describe the shape of your graph. Does this match yourprediction?
4 What was the temperature reading when it stopped falling?5 Use the graph to work out the melting point of the stearic acid.6 Explain in detail what is happening to the stearic acid particles at
this point.
Evaluating
7 a Describe how you could have carried out this investigationusing a thermometer instead of a datalogger.
b Which method is the most accurate? Explain why.
8 Describe how you could modify your investigation to prove thatmelting and freezing occur at the same temperature. If you havetime, carry it out.
Do not remove thetemperature probe fromsolid stearic acid.
Wash your hands, stearicacid can be harmful.
tripod
water
boiling tube
Bunsen burner
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I5aTeacher
activity notesHow quickly does heat travel?
Running the activityThis experiment can be done as a pupil experiment, but the result is a lot of very hot barsaround the laboratory. Pupils can take part in the demonstration by timing (and predicting thetime) when the drawing pins fall. Vaseline is preferable to candle wax for fixing the drawingpins to the bar, as it melts more easily.
Expected outcomesCore: Pupils see the vaseline melt and the pins drop. The pins nearest the flame fall first. Theparticles in the bar pass the energy from one to the next.
Extension: In their predictions, pupils might expect that the times between each pin fallingwould be equal. Pupils calculate the speed with which the heat was transferred to the first andlast pin and compare this with the graph to see if they match. From the graph they should seethat the time between each pin is not equal as the rate of heat flow will slow down furtheralong the bar, as the temperature gradient decreases.
PitfallsAbout five drawing pins is the maximum, or it takes forever for the last ones to fall. Pupils willhave difficulty recording minutes and part minutes – decide whether they should work inminutes and seconds, or minutes and decimals, or change to measure time in seconds. This isan extra complication if pupils are plotting a graph.
Safety notesThe bar gets very hot, stays hot for a long time, and doesn’t look hot.
ICT opportunitiesIt would be possible to set up a spreadsheet for the results and subsequent calculations of speed,and to draw the line graph.
AnswersCore:1 Pupils should predict that the heat will be transferred along the rod and cause the vaseline tomelt and the pins to fall. 2 Pupils should see that the time between each pin dropping getslonger as you move away from the flame. 3 Pupils should describe that as the heat energyreaches the particles they vibrate more and the energy is transferred from one particle to thenext by the vibrations.
Extension:1 Pupils should predict that the heat will be transferred along the rod and cause the vaseline tomelt and the pins to fall. 2 In their predictions, pupils might expect that the times betweeneach pin falling would be equal. Some pupils may predict that the time between each pin is notequal as the rate of heat flow will slow down further along the bar, as the temperature gradientdecreases. 3 The graph should have distance (in cm) on the horizontal axis, and time (inminutes) on the vertical axis. It should be a line graph. 4 Pupils calculate speed = distance divided by time. If the energy travelled at a constant speedthen the graph would be a straight line, and the numbers equal. 5 The experiment can becriticised as there is no measurement of how much vaseline is used. 6 Heat is lost to thesurroundings. Insulating the bar would prevent this (but is not practicable for this set up!). Witha very long bar eventually there would be no more heat flow along the bar, all would be lost tothe surroundings.
Type Purpose DifferentiationPractical Demonstration to show pupils how heat energy is transferred along a metal bar by
conduction.Core, Extension
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I5aTechnician
activity notesHow quickly does heat travel?
EquipmentFor each group/demonstration● metal bar, e.g. vertical from retort stand● retort stand, boss and clamp● four drawing pins● vaseline or candle wax● Bunsen burner● stopclocks for whole class
Unscrew the vertical from a retort stand and useanother retort stand, boss and clamp to hold ithorizontally. The clamp must be at one (the screw)end of the bar, even if it does sag a little bit. You mayneed to weigh down the retort stand base to keep itstable.
Fix five drawing pins to the lower edge of the barwith vaseline. The first pin should be 3 or 4 cm fromthe end of the bar, and the other three spaced atequal 3 or 4 cm intervals.
For your informationRunning the activityThis experiment can be done as a pupil experiment, but the result is a lot of veryhot bars around the laboratory. Pupils can take part in the demonstration bytiming (and predicting the time) when the drawing pins fall. Vaseline is preferableto candle wax for fixing the drawing pins to the bar, as it melts more easily.
Expected outcomesCore: Pupils see the vaseline melt and the pins drop. The pins nearest the flame fallfirst. The particles in the bar pass the energy from one to the next.
Extension: In their predictions, pupils might expect that the times between eachpin falling would be equal. Pupils calculate the speed with which the heat wastransferred to the first and last pin and compare this with the graph to see if theymatch. From the graph they should see that the time between each pin is notequal as the rate of heat flow will slow down further along the bar, as thetemperature gradient decreases.
PitfallsAbout five drawing pins is the maximum, or it takes forever for the last ones tofall. Pupils will have difficulty recording minutes and part minutes – decidewhether they should work in minutes and seconds, or minutes and decimals, orchange to measure time in seconds. This is an extra complication if pupils areplotting a graph.
Safety notesThe bar gets very hot, stays hot for a long time, and doesn’t look hot.
Running the activityPupils answer the questions on the pupil sheet using their knowledge ofconduction and insulation, and applying it to some practical applications.
AnswersCore:1 Particles in a gas like air are much further apart than those in a solid, so they do
not bump into each other as much, so it is more difficult for the particles topass on the energy.
2 Roof space/loft – stop heat being lost through roof to outside.Cavity walls – stop heat being lost through walls to outside.Windows – stop heat being lost through windows to outside.Carpets – stop heat being lost through floors to ground.
3 Good conductors – oven shelves, hob rings, pans, casserole dishes, kettleelements. Good insulators – oven and fridge doors, pan handles, oven gloves,bodies of electric kettles.
Extension4 Fur traps air, which is an insulator. On the inside it would trap the air more
efficiently.
5 a There are more layers of trapped air which insulate better.b Fluffing up the duvet traps more air between the feathers/filling which
insulates better.
6 a 40 years.b Sound insulation. Plastic frame requires less maintenance than wooden one.
Wooden frame may be rotten and need replacing anyway, so cost isdifference in prices, not total cost.
Type Purpose DifferentiationPaper To reinforce understanding of thermal conductors and insulators; and to see some
practical applications of conduction and insulation.Core (Extension)
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4 Explain why a fur-fabric coat might be warmer if you wear itinside out.
5 a Several layers of blankets are warmer than one thick blanket.Explain why this should be.
b Explain why you should ‘fluff up’ a duvet to be warmer.
6 aa To have a window replaced by one that is double glazed costs£200. The energy saved every year by just one window costs£5. How many years would it take for the double glazing to‘pay for itself’?
b What other reasons are there, besides heat insulation, forfitting double glazing?
I5bActivity
CoreHouse insulation
1 Explain why air is a better insulator thansolids like metal, brick and wood. (Hint:Think of the way the particles are arrangedin solids and gases.)
2 Each of the inset pictures shows somethingthat traps air inside it. Make a list of thefour ways the house is insulated. For eachone, explain where it stops the heat in thehouse being transferred to.
3 In the kitchen there are jobs for goodconductors and for good insulators. Makea list of as many as you can think of.
Running the activityPupils should work in pairs. Placing the crystal at the bottom and to the side ofthe water is fiddly. It would be worth demonstrating the technique to the pupilsand emphasising how difficult it is not to stir the water and spread the dyethroughout the liquid. Instructions are given on the activity sheet. Heating mustbe gentle. It would be best if the teacher visited each group, to help them turndown the gas and place the burner in the correct position. Pupils need to beencouraged to record their observations while the convection current is being setup.
Core: Pupils follow the instructions on the sheet and answer the questions.
Help: Pupils are given more guidance with the conclusion.
Expected outcomesThe water around the crystal becomes purple as the dye dissolves. The water onthe side of the beaker being heated expands, becomes less dense and rises, takingthe dye with it. The cooler, denser water away from the flame falls. As theconvection current is set up, the purple dye falls with the denser water that isaway from the flame.
PitfallsThe crystals must be placed carefully. Heating must be gentle (turn the gas down).
Safety notesEye protection should be worn. Care should be taken not to touch hot apparatus.The dye crystals – potassium manganate(VII) – should be handled with tweezers.Care should be taken not to get dye on skin or clothes.
AnswersCore:1 The purple dye dissolves in the water close to the crystal. The purple dye rises
on the side of the beaker that is heated. The purple dye falls on the side of thebeaker away from the flame.
2 Dissolving and convection.
3 The answers will reflect the understanding of the pupil. If the pupil has beenusing the red book, their answer should refer to density, and possibly toparticles. If using the green book, their answer will be restricted to hotter liquidrising and cooler liquid falling.
a The crystal is soluble and dissolves in the water.b (Green book users) It is hotter and therefore rises. (Red book users) The
particles in the water vibrate more, and take up more space. This means theliquid is less dense than the liquid around it, and rises.
c (Green book users) It is cooler and therefore sinks. (Red book users) Theparticles in the water are vibrating less than the particles above the flame.They therefore take up less space. This means the liquid is more dense thanthe liquid around it, and falls.
Help:4 Dissolves, rises, falls, convection, convection current.
● four small labelled pots of potassium manganate(VII) crystals
For your informationRunning the activityPupils should work in pairs. Placing the crystal at the bottom and to the side ofthe water is fiddly. It would be worth demonstrating the technique to the pupilsand emphasising how difficult it is not to stir the water and spread the dyethroughout the liquid. Instructions are given on the activity sheet. Heating mustbe gentle. It would be best if the teacher visited each group, to help them turndown the gas and place the burner in the correct position. Pupils need to beencouraged to record their observations while the convection current is being setup.
Core: Pupils follow the instructions on the sheet and answer the questions.
Help: Pupils are given more guidance with the conclusion.
Expected outcomesThe water around the crystal becomes purple as the dye dissolves. The water onthe side of the beaker being heated expands, becomes less dense and rises, takingthe dye with it. The cooler, denser water away from the flame falls. As theconvection current is set up, the purple dye falls with the denser water that isaway from the flame.
PitfallsThe crystals must be placed carefully. Heating must be gentle (turn the gas down).
Safety notesEye protection should be worn. Care should be taken not to touch hot apparatus.The dye crystals – potassium manganate(VII) – should be handled with tweezers.Care should be taken not to get dye on skin or clothes.
4 Complete the sentences to describe what is happening inside thebeaker by choosing some of the words below.
The purple dye in the water close to the crystal.
The purple dye on the side of the beaker that is heated.
The purple dye on the side of the beaker away from the flame.
This is one example of .
The movement of water is called a .
melts conduction insulator conductorconvection
convection current rises falls dissolves
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I6bTeacher
activity notesConvection currents around us
Running the activityThe activity is available at three levels but the contexts (sea breezes and hot water tanks) are common toall. Pupils should work alone or in pairs.
Core: This version is structured to tease out the explanation.Help: This requires almost no writing.Extension: This version gives little or no guidance.
Expected outcomesPupils can explain sea breezes in terms of a convection current, and why putting the heating element atthe top of a hot water tank is ill-advised.
AnswersCore:1 Rise. The air above the land is hotter than the surrounding air, because the land has heated it.
2 Once the heated air above the land has risen, cool air from over the sea will move in to take its place.
3 4
5 rise 6 The heated water is already at the top of the tank, so it stays at the top, unable to rise further.The water will continue to be heated, but the water in the tank will not mix. 7 The heated water risesand cold water moves down to take its place. This cold water is then heated. The resulting convectioncurrent ensures that all the water in the tank is heated evenly.
Help:1 Rise – see diagram above (arrow above land). 2 Sink – see diagram above (arrow above sea). 3 Seediagram above (circling arrows). 4 Away from the sea. 5 The water around the heaters – see shadedarea on tank diagrams above. 6 Rise – see diagrams above. 7 B 8 A
Extension:1 See diagram above. The air above the land is heated more than the air above the sea. This is because the land is hotter than the sea. The air over the land expands more than the air above the sea. This meansthat the air above the land is less dense than the air around it and rises, and the cooler, denser air fromabove the sea moves in to take its place. This means that there is movement of air from the sea to the land,and the air from the sea will be cooler than the air above the land, so will be felt as a cooling breeze. 2 See tank diagrams above. Placing the heater at the top of the tank only heats the water at the top of thetank. The hot water is less dense than the cold water, so the hotter water rises and the colder water sinks.This means that the cold water at the bottom will never come in contact with the heater. If the heater isplaced at the bottom of the tank the heated water will rise and unheated water will fall to take its place. In this way all the water in the tank will be heated.
A B
The sea is cooler than the land. The air above the sea is heated less than theair above the land.
The land is hotter thanthe sea. The air abovethe land is hotter thanthe air above the sea.
The sea is cooler than the land. The air above the sea is heated less than theair above the land.
The land is hotter thanthe sea. The air abovethe land is hotter thanthe air above the sea.
heater attop of tank
cold water in
heater atbottom of tank
coldwater in
A
B
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I6bActivity
ExtensionConvection currents around us
You are going to use your knowledge and understanding ofconvection to explain some observations.
1 Look at the diagram. It shows the air, the sea and the land on ahot day in summer.
1 Make a copy of the diagram. Add arrows to show the movementof the air. Explain in as much detail as you can why a cooling seabreeze blows on a hot summer’s day.
2 Hot water tanks contain a heater that heats thewater. The heater is a coil of metal that isheated using electricity.
When the heater is put at the top of the tank,as in tank A, only the water at the top of thetank is heated.
When the heater is put at the bottom of thetank, as in tank B, all the water in the tank isheated.
2 Copy diagrams A and B and label them toexplain why the heater should be placed at thebottom of the tank.
The sea is cooler than the land. The air above the sea is heated less than theair above the land.
The land is hotter thanthe sea. The air abovethe land is hotter thanthe air above the sea.
heater attop of tank
cold water in
heater atbottom of tank
coldwater in
A
B
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I7aTeacher
activity notesCooling by evaporation
Running the activityThe set-up will depend on the equipment available. If equipment is limited, youmay choose to demonstrate the activity. The temperature of the three pieces ofcotton wool should be measured for 10 minutes, with the outputs from all threeprobes being displayed in graphical form on the screen. Pupils then use theactivity sheet to guide them through writing an explanation of cooling byevaporation.
Core: Pupils write their own explanation using words given.
Extension: Pupils are asked to speculate on the difference between water andethanol.
Expected outcomesThe dry cotton wool should maintain a steady temperature. Both the water-soakedand the ethanol-soaked cotton wool should cool, with the ethanol-soaked cottonwool cooling more rapidly.
PitfallsThe measurements should be taken as soon as the ethanol and water are added tothe cotton wool. Delay may mean that all the ethanol evaporates before anymeasurements are taken.
Safety notesEthanol is highly flammable; there should be no naked flames in the vicinity.
AnswersCore:1 B
2 C
3 The liquid evaporates, turning into a gas. When this happens the particles withmore energy leave the liquid. This means that the particles in the liquid have lessenergy (on average), so the temperature of the liquid decreases.
4 Temperature probes A and B would return to room temperature.
Extension:5 (Most pupils) The ethanol must have evaporated more quickly than the water.
(Exceptional pupils) The forces of attraction between the ethanol particles mustbe weaker than those between the water particles, because more particles in theethanol had enough energy to leave the liquid.
Type Purpose DifferentiationPractical Demonstration to show that evaporation causes cooling. Core (Extension)
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I7aTechnician
activity notesCooling by evaporation
EquipmentFor each group / teacher demonstration:● three temperature probes● three clamp stands, bosses and clamps● cotton wool to wrap around temperature probes● three elastic bands to secure cotton wool● interface● computer● software so that data from temperature probes can be displayed
For the class:● water in labelled wash bottle● ethanol in labelled wash bottle
For your informationRunning the activityThe set-up will depend on the equipment available. If equipment is limited, theteacher may choose to demonstrate the activity. The temperature of the threepieces of cotton wool should be measured for 10 minutes, with the outputs fromall three probes being displayed in graphical form on the screen. Pupils then usethe activity sheet to guide them through writing an explanation of cooling byevaporation.
Core: Pupils write their own explanation using words given.
Extension: Pupils are asked to speculate on the difference between water andethanol.
Expected outcomesThe dry cotton wool should maintain a steady temperature. Both the water-soakedand the ethanol-soaked cotton wool should cool, with the ethanol-soaked cottonwool cooling more rapidly.
PitfallsThe measurements should be taken as soon as the ethanol and water are added tothe cotton wool. Delay may mean that all the ethanol evaporates before anymeasurements are taken.
Safety notesEthanol is highly flammable; there should be no naked flames in the vicinity.
Type Purpose DifferentiationPractical Demonstration to show that evaporation causes cooling. Core (Extension)
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5 Suggest why the temperature of probe B fell more quickly thanthe temperature of probe A.
I7aActivity
CoreCooling by evaporation
You are going to use temperature probes to monitor cooling byevaporation.
1 Soak the cotton wool around temperature probe A with water.2 Soak the cotton wool around temperature probe B with ethanol.3 Leave the cotton wool around temperature probe C dry.4 Monitor for 10 minutes, displaying the output from all three
temperature probes.
1 Which temperature probe was cooled the most?2 Which temperature probe was cooled the least?3 Explain why the temperature of the liquids around temperature
probes A and B decreased. Use these words in your explanation:
4 Predict what would happen when all the liquid had evaporatedfrom the cotton wool around temperature probes A and B.
temperatureprobe Atemperatureprobe Btemperatureprobe C
particles energy less
evaporates
temperature
liquid gas more
Extension
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I7bTeacher
activity notesRadiation
Running the activityThis is a quick but effective teacher demonstration. One of two aluminium foil piedishes is painted matt black on one surface. A coin is stuck to the other surfaceusing wax. A coin is also stuck with wax to the same surface of the unpainted piedish. A Bunsen burner is lit and the teacher holds the pie dishes equidistant fromthe flame (about 15cm) using retort stands and clamps, with the coins away fromthe flame. During the demonstration the teacher should remind the pupils thatinfrared radiation is like light, and that light is absorbed by black surfaces butreflected by silver surfaces.
Expected outcomesThe wax holding the coin in the painted pie dish melts first and the coin dropsoff. After a delay, the other coin drops off. Pupils should understand that the shinypie dish reflects infrared heat back and so doesn’t heat up as much as the mattblack pie dish which absorbs heat.
Safety notesWarn pupils not to touch the hot aluminium pie dishes.
Type Purpose DifferentiationPractical Demonstration to show that shiny silver surfaces reflect more infrared radiation than
matt black surfaces.No pupil sheets
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I7bTechnician
activity notesRadiation
EquipmentFor the teacher demonstration:
● one aluminium pie dish● one aluminium pie dish painted matt black on underside● two coins (e.g. 1p)● candle so that coins can be fixed to dishes● Bunsen burner● two retort stands and clamps
For your information
Running the activityThis is a quick but effective teacher demonstration. One of two aluminium foil piedishes is painted matt black on one surface. A coin is stuck to the other surfaceusing wax. A coin is also stuck with wax to the same surface of the unpainted piedish. A Bunsen burner is lit and the teacher holds the pie dishes equidistant fromthe flame (about 15 cm) using retort stands and clamps, with the coins away fromthe flame. During the demonstration the teacher should remind the pupils thatinfrared radiation is like light, and that light is absorbed by black surfaces butreflected by silver surfaces.
Expected outcomesThe wax holding the coin in the painted pie dish melts first and the coin dropsoff. After a delay, the other coin drops off. Pupils should understand that the shinypie dish reflects infrared heat back and so doesn’t heat up as much as the mattblack pie dish which absorbs heat.
Safety notesWarn pupils not to touch the hot aluminium pie dishes.
Type Purpose DifferentiationPractical Demonstration to show that shiny silver surfaces reflect more infrared radiation than
matt black surfaces.No pupil sheets
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I7cTeacher
activity notesThe vacuum flask
Running the activityIf there is a vacuum flask available, especially one that can be taken apart, set thescene by showing it to pupils. An old, broken one can be used to demonstrate thedouble skin, but be careful with sharp broken glass.
ICT opportunitiesPupils could search the Internet for further information about James Dewar andthe vacuum flask.
Type Purpose DifferentiationPaper Pupils apply the ideas studied in the last three lessons to explain how a vacuum flask
works.Core
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I7cActivity
CoreThe vacuum flask
You are going to learn about Sir James Dewar, a Scottish scientistwho lived over a hundred years ago. He invented a container tokeep very cold liquids cold that is very useful today.
James Dewar (1842– 1923) was interested in what happened at verylow temperatures. He worked on liquefying the gases in air(changing them from gases to liquids). By 1885 he could producelarge quantities of liquid oxygen. By 1898, he was the first scientistto cool hydrogen gas to its boiling point of −252°C. In 1899, he wasable to solidify it at −259°C.
Dewar needed a way to keep these liquids very cold, and in 1892 heinvented the first vacuum flask (sometimes called a thermos flask,after the first commercial version, made in 1904).
A vacuum flask can keep hot things hot, and cold things cold!
1 The double skin of the flask is made of glass, which is a poorconductor. It is coated with a shiny silver coating on both insidesurfaces. What is the function of the coating?
2 Between the two layers making the double skin there is avacuum, which stops heat being transferred in two differentways. What are these two ways?
3 The top of the flask in Dewar’s day had a cork stopper. Nowadaysit is usually hollow plastic. Why doesn’t the flask have a metaltop?
4 What kind of heat transfer does the top of the flask prevent whenit is put on the flask?
Running the activityPupils answer the questions on the pupil sheet to analyse the graph.
AnswersCore:1 Beaker A.
2 There is more surface area, so more convection currents in the air above, andmore evaporation. In terms of particles, there are more air particles in contactwith the hot water to carry heat energy away in convection currents. There ismore chance for liquid particles to escape from the container with the largersurface area by evaporation because it takes energy to break the bonds betweenthe liquid particles.
3 How much water, start temperature, room temperature, surface area (or size ofbeaker), material of beaker, lid or not, insulation round beaker. N.B. Becausequestion says ‘how quickly’, time is not a variable as we are looking at rate.
4 They changed surface area (size of beaker); they controlled the rest.
5 Temperature or rate of cooling.
Extension:6 Rate = (80 − 59)/10 = 2.1°C/minute.
7 Curve A is steepest at the start, showing that the liquid cools fastest when it ishottest, i.e. when the temperature difference between it and the surroundings isbiggest. The bigger the temperature difference, the more convection currents asthe greater the density difference between air in contact with the hot liquid,and surrounding air; also the greater the rate of conduction through the beakersides. In addition evaporation is faster at higher temperatures.
Type Purpose DifferentiationPaper Pupils analyse two cooling curves, and identify the variables in the experiment. Core (Extension)
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6 The temperature after 10 minutes in curve B is 59°C. Calculatethe cooling rate of the water, in °C per minute.
7 Look at curve A. Is it steepest at the start or at the end? Whatdoes this show? Why do you think it happens?
I8aActivity
CoreWhat affects how tea cools?
You are going to look at the cooling curves from twodifferent cups of tea and analyse them.
Sam and Alex had two mugs, one was 10cm across thetop, the other was only 5cm across. Both mugs weremade of plastic. They poured exactly 200cm3 of hotwater into each one, and put a temperature probe intothe water. When the temperature cooled to 80°C theystarted recording, and recorded the temperature for 10minutes.
Here is the graph of their results.
1 Which beaker cooled down fastest?
2 Suggest why this happened. Use the words ‘energy’ and‘particles’ in your answer.
3 Make a list of all the things that could affect how quicklythe water cooled down. These are the independent variables.
4 Which of the independent variables did Sam and Alex change? Which did they control?
5 What was the dependent variable in the experiment?
Review learning● Set the questions for individuals to consider and suggest
answers to. Then ask them to share their responses withother pupils.
● Pupils can summarise the suggestions and record them intheir books, to reconsider after further lessons.
● Hold up each example thermometer in turn, and ask avolunteer to describe how and where to use it.
Sharing responses● Teacher-led discussion of the outcomes from Activity I1a.
● Discuss and evaluate the accuracy of the waterthermometers made by gathering class results for thetemperatures measured.
Group feedback● Pupils work in groups to complete answers to the questions
on the pupil sheet.
● Take suggestions from the groups and sum up on theboard.
Word game● Play a game of hangman with the whole class to reinforce
vocabulary and spelling.
● Teacher puts up hangman dashes for each name ofthermometer, pupils guess letters until they guess the word.
Looking ahead● Ask a group of 12 to 16 pupils to model being a solid, with
each pupil having left hand on shoulder of pupil in front,and right hand on shoulder of pupil at side. Say they aregiven a small amount of energy to allow them to move andvibrate more without breaking bonds. This may be bestdone in a corridor or playground if the classroom iscrowded.
QuestionsWhy do we need thermometers?
Why isn’t just feeling it good enough?
➔ Pupil sheet
Answers1 mercury: glass would crack,
temperature too high for scale,mercury might boil/scale does not gohigh enough
Suggested alternative plenary activities (5–10 minutes)
Review learning
Show the pupils the learningobjectives again. Ask volunteers toexplain how the lesson has helpedthem to achieve the objectives.
Sharing responses
Pupils answer questionsabout Activity I2a.
Group feedback
In groups, pupils completethe sentences about thedifference between heat and temperature.
Word game
Play the Taboo game.
Looking ahead
A small group of pupilsmodel a solid as heatenergy causes increasedvibration and expansion.
Review learning● Pupils volunteer to explain how the lesson helped them achieve each objective.● Objective 1: The difference between energy and temperature is modelled in the
textbook as the total thermal energy of all the particles in the system; while thetemperature is the average kinetic energy per particle.
● Objective 2: The two independent variables in the activity are quantity of waterand temperature rise, while the dependent variable is the quantity of energyused. Pupils must appreciate that when there are two independent variables, onemust be controlled (they all used the same temperature rise).
Sharing responses● Pupils can use individual whiteboards (or ice cream tub lids) with whiteboard
pens to answer the questions read out from the teacher sheet so you can checkthat all respond, and judge whether the lesson objectives have been learned. Ifindividual whiteboards are not available then pupils can volunteer to answer.
Group feedback● Pupils work in pairs and then in fours to complete the sentences below. Ask a
volunteer for each group to read out an answer.● Questions
1 We explain the difference between heat and temperature by saying …2 A large jug of hot water has more energy than a mug of hot water because …3 A large mug of coffee cools down more slowly than a small cup because …
● Answers1 … heat is a kind of energy – the total energy that all the particles possess. It ismeasured in joules with a joulemeter. Temperature is hotness, it depends on theaverage kinetic energy of the particles. It is measured in degrees Celsius with athermometer or temperature probe. 2 … the large jug contains more waterparticles, all with kinetic energy. 3 … the large mug has more particles, and all the particles must lose some energy for the drink to cool down.
Word game● Pupils play Taboo using cards cut out from the pupil sheet.● Give one pupil a card with a mystery word on it. The pupil offers clues to the
class to allow them to identify the mystery word, but is not allowed to use thegiven ‘taboo’ words in their clues.
● You can adjust the level of challenge by banning the use of just the first, or firstand second words in the taboo list, and then increase the number later.
Looking ahead● Ask 12 to 16 pupils to stand in a grid arrangement, modelling a solid with the
left hand on shoulder of pupil in front, right hand on shoulder of pupil at side.Both arms should be kept bent at the elbow as much as possible. Initially they are‘very cold’ – can’t move at all.
● Say they are now supplied with energy and can move – but must keep both handstouching neighbours’ shoulders but can now straighten arms. The group can beseen to take up more space, modelling thermal expansion. The ‘particles’ getfurther apart – they (the pupils) do not themselves expand.
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I2 PlenariesTemperature and energy
Sharing responsesTeacher sheetRead out the questions below to the class.
1 What do particles gain when they get hotter? [energy]
2 What are the units of energy? [Joules]
3 What are the units of temperature? [°C]
4 What independent variable did we change in the heatingexperiment? [water volume]
5 Which independent variable did we control in the heatingexperiment? [temperature rise]
6 What was the dependent variable in the heating experiment? [energy used]
Review learning● Pupils either answer on white boards (or lids of ice cream
tubs) so that a whole-class response can be quicklygathered, or select volunteers to answer.
Sharing responses● Sum up after the activity by asking volunteers to describe
first what they observed and then other volunteers toexplain the observations.
Group feedback● Pupils produce posters to explain how a thermometer
works (you need to specify a liquid in glass thermometer,rather than a temperature probe, etc.), using expansion/contraction ideas and including a diagram of particles.
● The posters can be displayed for discussion now, or todiscuss as the starter for the next lesson.
Word game● Pupils work in pairs to match the observation with the
correct explanation.
● Check the correct answers at the end. (This sheet couldbe used as a starter for the next lesson.)
Looking ahead● Ask 12 to 16 pupils to form a regular array, modelling a
solid with left hand on shoulder of person in front, righthand on neighbour’s shoulder.
● Tell pupils then to ‘melt’ and move so that they arealways touching at least one person, but keep swappingpartners (say every 3 seconds).
● Then tell pupils to form a gas by walking freely instraight lines, only changing direction when they collidewith a wall or each other.
● With some classes you can extend this into a game bycalling ‘melt’, ‘boil’, ‘freeze’ ‘condense’, etc.
Telephone wires always sagbetween poles, they arenever stretched.
A gas-filled thermometer ismore sensitive than a liquid-filled one
In the olden days the metal‘tyres’ for cartwheels wereheated before being fittedon the wheel.
Putting a screw-topped jarin hot water makes it easierto open.
Furniture often creaks atnight.
Concorde is shorter before ittakes off than when it isflying.
Explanation
The tyre expanded when itwas hot, so it slipped roundthe wheel easily, and thenwhen it cooled it held ontothe wheel tightly.
The metal lid expands morethan the glass jar.
If they were tight to beginwith, and the weather gotcolder, they would snap asthey got shorter.
In flight, friction with the airmakes the plane heat upand expand.
Gases expand more thanliquids for the sametemperature rise.
The furniture expandsduring a hot day, and thenshrinks back during a coolernight.
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I4 PlenariesAll change
Review learning● From the jumbled up words on the pupil sheet, pupils
decode the words relating to changes of state.● Then ask pupils to write a definition for each word –
more than one sentence is possible for each.● Take feedback from pupils. Summarise on the board.
Identify the importance of using scientific vocabulary.
Sharing responses● Whole-class discussion of the outcome of Activity I4a.
This should include the shape of the graph, how to readthe melting point off the graph and an explanation ofwhat is happening in terms of the particle model.
Group feedback● In groups, pupils look at the temperature–time graph on
the pupil sheet, which represents heating ice from –10°Cto 120°C. They discuss what is happening in eachsection, and explain the shape of the graph.
Problem solving● Set up a kettle with a temperature probe clamped in the
water (not touching the element) and connected to adatalogger displaying a temperature graph.
● When the kettle boils, point out the steam and ask forsuggestions as to why a burn from the steam would bemore serious than one from the boiling water. If theexplanation from pupils is not forthcoming, explain thereason and check understanding.
Looking ahead● Ask 12 to 16 pupils to model heat conduction in a (non-
metallic) solid. They line up with linked arms in a line.Tell them you have given heat energy to the end pupil,who begins to jump around (still linked). This movementis passed to the next in line, and so on.
● Explain that this is a particle model of one way in whichheat energy can travel through a solid, and that nextlesson the class will see this in action.
➔ Pupil sheet
Answersmelting – solid to a liquidboiling – liquid to a gascondensation – gas to a liquidfreezing – liquid to a solid
➔ Pupil sheet
Equipmentkettle (if it has automatic cut-off you mayhave to hold the switch when it boils),temperature probe and datalogger, retortstand and clamp.
Safety: steam burns – be careful, especiallywhen holding in the cut-out switch.
Review learning● Ask pupils to give three differences between conduction
and convection.
Sharing responses● Ask volunteers to describe what they observed in Activity
I6a. Then ask for other volunteers to explain why thishappened.
Group feedback● In groups, pupils discuss how they would use the
experiments they have seen to describe what aconvection current is, and explain why it happens.
● Collect responses from groups and summarise on theboard.
Word game● Pupils create a ‘poem’ by writing the word CONVECTION
down the page, and writing sentences about the key ideasin the lesson going across.
● Show them the example for CONDUCTION from theteacher sheet to inspire them.
Looking ahead● Wipe a little surgical spirit/ethanol/water on pupils’ skin,
or wet one of a pupil’s hands and direct a cold fan atboth hands. Ask the pupil to observe the temperaturedifference.
● Pupils should feel the effect of the liquid evaporatingfrom the skin.
● By asking what is happening, find out whether pupilsknow the word ‘evaporation’, and what it means.
AnswersConduction is best in solids; convection isonly in liquids and gases; heat can travelin any direction by conduction; heat canonly travel upwards by convection; inconduction only the energy travels; inconvection the material does too.
AnswersLower ability: particles rise and transferenergy until temperature is the same in allof the liquid.
Higher ability: relate to thermal expansionin liquids and lower density causing liquidto rise until temperature is the same in allof the liquid.
Review learning● Ask pupils to complete the wordsearch on the pupil
sheet.
● Ring the words on a copy of the pupil sheet and show it as an OHT for them to check their answers. Use thewords on it to introduce the lesson.
Sharing responses● Ask volunteers to describe what they observed in
Activity I7a. Then ask for other volunteers to explainwhy this happened in terms of particles.
Group feedback● Explain that most heaters, including so-called radiators,
are convectors not radiators.
● In groups, pupils use their observations from ActivityI7b to consider whether all ‘radiators’ should be paintedblack.
● Then collate their views on the board. Black is best as itradiates most heat – so heaters would be more efficient,but there are aesthetic considerations too.
Word game● Pupils match up the beginnings and endings of
sentences so that each statement is an observationfollowed by a sensible qualifier/explanation.
● The cards could also be used as a loop game.
Looking back● Pupils revise and consolidate knowledge from the unit.
They can use the Unit map, Pupil checklist, or the Testyourself questions.
Evaporation causes coolingbecause it takes energyfrom the surroundings to …
Evaporation happens fasterin a flat open dish …
Evaporation happens fasterin a draught because …
Endings
… of heat transfer that canget through a vacuum.
… has no particles in it atall.
… the draught carries theparticles away.
… break the bonds betweenthe particles in a liquid.
… reflector of heatradiation.
… because there is moresurface area for the particlesto escape from.
… reflector of heatradiation.
… turns to a gas, withoutboiling.
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I8 PlenariesExplaining the results – Think about
Group feedback● Pupils work in groups on an explanation of why it is
important to identify all the variables in aninvestigation. For instance in an experiment to find outwhether dissolving salt in water makes it evaporatemore, what would be the variables?
● Then ask pupils to decide how they could control eachindependent variable. If there is time, pupils coulddesign the experiment, drawing apparatus and planninghow to obtain evidence.
● Ask for volunteers from each group to share what theyhave discussed and summarise for the whole class.
Bridging to other topics● Give groups of pupils one or two of the examples
opposite of things that are affected by more than oneindependent variable. Ask them to say what thevariables are.
● Ask for volunteers from each group to share what theyhave discussed and summarise for the whole class.
Examplesdensity, speed, how fast an animal can run,pulse rate, number of rabbits on thecommon, how quickly sugar dissolves in adrink, the size of a Bunsen burner flame,the heat energy given out by burning fuel,the brightness of bulbs in a circuit
1 Sean and Ellen heated three blocks of metal by 40ºC.The energy needed to increase their temperature by40ºC was measured. Each block weighed 100 g. Here are the results.
a Show this information as a bar graphon the grid opposite.
b Which metal needed the most energyto increase its temperature by 40ºC?
c This experiment was a fair test. Lookat the list below. Tick all the correctreasons why it was a fair test.
The metal blocks were different masses.
The temperature was raised by the same amount for each metal.
A different temperature rise was used for each metal.
The metal blocks were the same masses.
d To heat the same mass of copper bythe same temperature rise asaluminium, you would need:
I5 Conduction1 conduction – Energy passing along a solid from
the hotter end to the cooler end.thermal conductors – These conduct thermalenergy well.thermal insulators – These are poor conductorsof thermal energy.
2 a falseb truec true
3 a Coloured red – cooking foil, saucepanb Coloured blue – expanded polystyrene cup,
cling film, water, air, vacuum flask
I6 Convection1 a liquids, gases, solids
b thermalb current, liquid, gasd rises, falls
2 C3 a false
b falsec trued true
I7 Evaporation, radiation1 evaporate – When a liquid turns to a gas by
taking in energy from around it.infrared radiation – This is given out by any hotobject. It acts like light.Thermal energy can be transferred by … – infrared radiation.
2 The energy to turn the liquid sweat into gas istaken from my body.
3 radiation4 a Coloured green – bar heater, fan heater,
radiator, saucepanb Coloured red – bar heater, radiator, electric
hobc Coloured blue – saucepan
I8 Explaining the results1 a
b copperc Ticked – The temperature was raised by the
same amount for each metal. The metalblocks were the same masses.
5 Remember that, on the Kelvin temperature scale, the lowestpossible temperature is 0K (nought degrees Kelvin). This is thesame as –273°C on the Celsius scale.
a On the Kelvin scale what is:i the boiling point of water?ii the freezing point of water?iii the melting point of lead (which is 328°C)?iv the difference between the freezing point of water and the
boiling point of water?
b i What do scientists call the lowest possible temperature?ii Explain why it is impossible for anything to be colder than
this temperature.
c i The temperature of a plumber’s blowtorch flame is about1773K. Why is lead a good metal to put into the solderthat plumbers use to join pipes together?
ii Water pipes are usually made from copper. What must bethe lowest possible melting point of copper, given that thepipes do not melt when plumbers use a blowtorch onthem?
6 The diagram shows a metal cube filled with hot water at 60°C.Ed touches the sides to find out if the surfaces feel the same.
a All the sides feel warm. Using ideas about energy transfer,explain why Ed’s hands feel warm when he touches the sidesof the cube.
b After thirty minutes, the water inside the cube is at the sametemperature as the air outside it. Explain why this hashappened.
1 Write down the following in the order in which they would boil. Put the quickest first. Use the letters for your answer:
A a half-full kettle of water.
B a half-full bath of water.
C a full kettle of water.
D a full bucket of water.
E a swimming pool full of water.
2 Tom puts one litre of water, at 20°C into a kettle and heats it up.After three minutes the temperature is 57°C.
He repeats the experiment with a different amount of water. This time, the temperature rises to 74°C in three minutes.
a Why did Tom heat both of them for three minutes?
b What was the rise in temperature in the first experiment?
c What was the rise in temperature in the second experiment?
d i Did Tom use more water or less water in the second experimentthan in the first?
ii Explain how you reached your answer.
CORE
3 a Write down the following in their order of energy content. Start withthe one that contains the least energy. Use the letters for your answer:
A 10cm3 of water at 10°C.
B 100cm3 of water at 99°C.
C 100cm3 of water at 10°C.
D 100cm3 of water at 50°C.
E 10cm3 of water at 5 °C.
b Explain why 1kg of solid gold contains less energy than 1kg of liquid gold.
c 1g of iron, at 20°C, contains less energy than 1g of water at 20°C.Explain what this tells you about the number of particles in 1g of water compared with the number of particles in 1g of iron.
4 Reptiles need to warm up their blood, before they can become really active, by lyingin the sun. The bigger the reptile, the longer it needs to lie in the sun before it feelsactive enough to hunt.
a Explain why a snake with a mass of 1500g must lie in the sun longer thananother snake with a mass of 500g.
b In the UK, the only poisonous snake is the adder. You are much more likely to bebitten by an adder in the afternoon than early in the morning. Explain why.
c Some lizards can flatten out their bodies, when they lie in the morning sun.Explain how this helps these lizards to warm up quickly.
5 Fire fighters often extinguish fires with water. This not only puts out the flames but italso cools the burning material.
Two fire crews are tackling fires in separate wood yards. Crew A are fighting a firewhere there are 15000kg of wood on fire. In Crew B’s fire there are 1000kg of woodburning.
a i Which fire crew would need to use the most water?ii Explain your answer in terms of energy.
b In terms of the fire triangle, which aspect of the triangle have the fire crewsremoved when they put out the fire?
6 Look at the data in the table below. It shows the final temperature reached when asubstance from column 1 was mixed with a substance from column 2 in an insulatedcontainer.
a i Which of the lettered substances X, Y and Z contained the most energy?ii Explain your answer.
b i What would happen to the final temperature reached, for substance X, if thesame amount of X was put into twice the volume of water?
Material Physical Nature of the particles Amount of energystate in material
Cold Solid All touching in a regular Lowcopper arrangement and vibrating
a little.
Hot A All touching in a regular Bcopper arrangement and vibrating
very fast.
Copper Gas C Very high
Copper Liquid D High
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I3 HomeworkBigger and smaller (continued)
c Water pipes are usually made from copper. Sections of pipeare held together with solder, which can stretch withoutcracking. Explain why the solder in the pipes in a centralheating system must be able to stretch.
d The diagram showsa metal bridgeacross a river. It wasbuilt with a gap atone end.
Explain why there isa gap in Decemberbut not in July.
EXTENSION
4 John warms a large flask, as shownin the diagram.
a Explain why John sees bubblescoming out of the tube.
b i What will happen if heremoves his hands from theflask but leaves the tube inthe water?
ii Explain why this willhappen.
5 a Calculate the densities of thefollowing materials:i a piece of lead having a mass of 22.6g and a volume of
2cm3.ii a block of iron having a volume of 200cm3 and a mass of
1580g.
b i Calculate the volume of a piece of copper having a massof 450g and a density of 8.9g/cm3.
ii Explain what will happen to the number of particles andthe volume they occupy, if the piece of copper is heated.
1 Copy and complete the diagram below, filling in the spaces. Use onlywords from the list.
2 a Use the data in the table below to draw a graph. You will need some graph paper.
b The substance was a liquid at the start. What is happening to its state between 4 minutes and 7 minutes?
c What is different about the particles in the substance at 8 minutescompared with at 1 minute?
CORE
3 a Look at the data given for question 2a. Sketch the shape of the graph you would obtain if you had started with the substance at23°C and heated it up to 30°C.
b Explain how the arrangement of the particles would change ifyou continued to heat the substance until it became a gas.
c Explain what is happening to all the energy you put into the substance.
EXTENSION
4 a Explain, in terms of changes of state, what scientists mean when theytalk about a reversible process.
b i Sketch the shape of the graph you would expect to obtain if youheated some ice, at −10°C until it had all become steam at 110°C.
ii Explain the shape of graph that you have drawn.
c First aid books often say that a burn from steam at 100°C is muchworse than a burn from boiling water at 100°C. Using yourknowledge of particles and energy, explain why this is true.
d Describe how the forces of attraction between water moleculeschange as it condenses from steam to liquid water.
condensing liquid freezingboiling
Time in minutes 0 1 2 3 4 5 6 7 8
Temperature in °C 30 28 26 25 24 24 24 24 23
solidmelting
gas
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I5 HomeworkConduction
HELP
1 Sam’s granddad has made a cup of tea in a plastic mug. He left the metalspoon in the tea while he answered the telephone.
Write sentences about conduction to explain each of the followingobservations:
a The spoon was hot when Sam’s granddad came back from thetelephone.
b The mug handle was not hot after the telephone call.
c The metal spoon cooled down quickly when cool water was run onto it.
d Sam’s grandma’s mug, made from metal, burned her lips when shetried to drink her tea from it.
2 a Sam wanted to find out more about conduction. She made three cubes.The first was made from solid copper. The second was a copper boxfilled with water. The third was a copper box filled with air.
Sam put the same Bunsenflame underneath eachbox. She put athermometer above eachbox. She heated each boxfor 5minutes.
Copy and complete thefollowing sentences:i The thermometer
that reached thehighest temperaturewas the one abovethe solid copper box because …
ii The thermometerabove the air-filledbox hardly warmedup at all because …
b Normal double-glazing is made from two layers of glass with air trappedin between them. Complete the following sentence:
Normal double-glazing helps to keep houses warm because …
3 a Loft insulation is a loose fibre roll that traps heat inside the house. Explain why ittraps heat in the house.
b Hot water cylinders in new houses are surrounded by a thick layer of polystyrenefoam. What property does the polystyrene foam have?
4 Joel set up an experiment like the one shown in thediagram.
He used five different rods, all the same length.He heated the rods and timed how long it tookfor the drawing pin to drop off. He recorded hisresults in the table shown below.
a Which material is the best conductor of heat?
b Which material is the worst conductor of heat?
c The experiment shows that some solids conduct heat much better than others.Using a particle model, explain why all solids conduct heat better than gases.
EXTENSION
5 a Using ideas about particles, explain how the heat from a cup of coffee transfers tothe end of a spoon held in your hand, when you are stirring the coffee.
b Explain why the heat of the sun cannot possibly reach the Earth by conduction.
c Fred is a farrier. He shoes horses. He cools his horseshoes by putting them into atank of cold water, after they have been in the furnace. Each horseshoe comes outof the furnace at about 1000°C. The water temperature rises by about 1 °C everytime he puts a hot shoe into it.i Explain why the horseshoe cools by over 900°C but the water temperature
only rises by a few degrees.ii Explain why the shoe would cool much more slowly if Fred just held it in the
1 a Complete the wordsearch by finding the following wordsabout heat. You will need a copy of the wordsearch onsheet 3.
b Write down the word in the list that is about heat transferwhen the heat moves along an object.
c Write down the two words that go together to describe theway heat is transferred through liquids and gases.
d Write down the word that means the same as heat.
e Write down the word that is something you can measure toshow how hot a substance is.
CORE
2 a Write a couple of sentences to explain how thermal energyfrom a radiator reaches the other side of a room.
b Gliders use convection currents to gain height. If there areno convection currents the glider will descend. Explain whygliders rise when over a town.
c Sea breezes are caused by convection currents. Theysometimes cause a cool breeze to blow in off the sea. Copythe diagram below and then add arrows to show howconvection currents could be caused by warm air rising overthe land.
3 The diagram shows a hot air balloon with itspilot. The pilot controls the height of theballoon by turning a gas burner on and off.If he wants to go up, he turns the burner on.He turns it off to descend.
a Explain why the pilot must ignite theburner to ascend.
b To keep the balloon at a constant height,the pilot gives occasional blasts on theburner. Why must he do this?
c If the pilot wants to descend quickly he canpull a cord to create a hole in the top of theballoon. Explain why this speeds up hisdescent.
d When he is setting off the pilot must first inflate the balloon.He does this by having a ground crew hold the bottom of theballoon wide open. Then he points his burner into the holethey have made. Slowly, the balloon inflates.
Explain why directing the burner into the hole created by theground crew inflates the balloon, when all the pilot is doing isheating up the air that is inside it.
4 It is bonfire night and Zena and her friends are having a bonfireparty. Zena notices that the smoke from the fire is rising veryquickly. She knows that smoke is tiny particles of soot. Describewhat you would say to her to explain how these particles arebeing made to rise so quickly.
1 Look at the diagrams. They all show a use of either evaporation or radiation. Writetwo headings ‘Evaporation’ and ‘Radiation’in your book and write each of the lettersfrom the diagrams under the correct heading.
2 James has a dish containing some copper sulphate solution. He wants to grow some crystals of copper sulphate. To do this he must evaporate some of the water from thesolution.
a James decides to warm the solution. He uses a Bunsen burner with the air hole half open. Explain why this will help himto get some crystals quickly.
b James thinks that his evaporation is a bit slow, so he fullyopens the air hole on his Bunsen burner. Write a sentence to explain why this speeds up the evaporation.
CORE
3 Pedro is a painter and decorator. He cleans his brushes in aspecial brush-cleaning fluid. If he spills some on his hands theyfeel very cold as they are drying off.
a Using ideas about energy movement, explain why Pedro’shands feel cold when he spills brush cleaner onto them.
b The brush cleaner dries off faster on Pedro’s hands than itdoes if he spills some on his painter’s apron. Explain why.
4 Jasmine is sitting in her room. She has her central heating radiatoron but is still feeling cold. She turns on her electric bar fire. Shecan feel the heat from the electric bar fire coming straight at her.She cannot feel the heat from the radiator in the same way.
a How is the thermal energy from the radiator being transferredto Jasmine?
b How is the heat from the electric bar fire being transferred toJasmine?
c i Which of the heaters might cause Jasmine’s skin to burn,as it would if she stayed in the sun for too long?
ii Explain how you chose your answer.
d i Which of the heaters would be able to transfer thermalenergy if it were used on the Moon?
ii Explain why only this heater would work on the Moon.iii Scientists have observed that the temperature on the
Moon’s lit side is high but the temperature on its dark sideis very low. Explain this observaton.
EXTENSION
5 a When young children have a fever their skin becomes veryhot. Parents say that they are ‘burning up’. Suggest where thethermal energy, that makes their skin so hot, has come from.
b Suggest how this thermal energy reaches the skin.
c One way to help the sick child is to remove their clothes,sponge them with tepid (slightly warm) water and leave themto dry in the air. Explain how ‘tepid sponging’ will help tolower their temperature.
d Dr Turner took an infrared photograph of a child with a feverand compared it with a similar child who did not have afever. Describe how the two photographs would be different.
6 Some young people are doing a sponsored walk across somemountains in the Lake District. One of them is injured and a walkofficial tries to prevent the walker from getting too cold while themountain rescue team arrives. The mountain rescue doctorcovers the casualty with a bubble-wrap layer and then with ashiny silver survival blanket.
a What thermal energy transfer processes would have causedthe walker to cool down too much?
b How could the walk official have prevented this fromhappening?
c Why did the doctor use a bubble-wrap layer first?
d How could the shiny survival blanket help to keep thecasualty warm?
1 a A = 97 °C; B = 34 °C; C = −5 °C; D = 25 °C (Accept 20–30) ; E = 37 °C 6One mark for each correct temperature plus 1 mark if units included at least once.
b In a science lab. 1
c To take a child’s/person’s temperature or on a fish tank. 1
d Thermal energy. Accept ‘heat’. 1
e i 100 °C is the boiling point of water. Underscore shows the pupil response. 1
ii Water freezes at 0 °C. Underscore shows the pupil response. 1
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COREQuestion Answer Mark
2 a Thermal energy. Accept ‘heat’. 1
b There is less thermal energy inside the fridge than outside it because the fridge 1has transferred the energy to the panel at the back. Accept equivalent answers. 1
3 a When I am having a bath, thermal energy transfers from the water to my body. 1Underscore shows the pupil response.
b Water in an electric kettle gets hot because thermal energy is transferred from 1the element into the water. Underscore shows the pupil response.
4 a The gas at –245 °C is colder. 1
b The Celsius scale goes downwards from zero/they are negative numbers. 1Accept equivalent answers.
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EXTENSIONQuestion Answer Mark
5 a i 373K 1
ii 273K 1
iii 601K 1
iv 100K 1
b i Absolute zero. 1
ii All the energy has gone at absolute zero. 1
c i It melts easily. 1
ii 1774K/Above 1773K. Accept equivalent answers. 1
6 a Thermal energy from the water 1flows evenly through the metal sides 1into Ed’s hand, warming it up. 1
b Some of the energy inside the cube, which made it hot, has transferred to the 1air outside the cube.Now each particle inside the cube has the same amount of thermal energy 1as each particle outsideso the temperatures are the same. 1
1 A somewhere before C. C somewhere before D. D somewhere before B. 4B somewhere before E. One mark for each correct answer.
2 a To make it a fair test. 1
b 37 °C (1 mark for the numerical value; 1 mark for the unit) 2
c 54°C 1
d i Less 1
ii The temperature rose further/higher/more 1for the same amount of heating. 1
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COREQuestion Answer Mark
3 a E somewhere before A. A somewhere before C. C somewhere before D. 4D somewhere before B. One mark for each correct answer.
b Liquid gold must be at a higher temperature than solid gold. 1Both have the same number of particles. 1So the one at the higher temperature has the most energy. 1Accept equivalent answers.
c Both have the same mass. 1So the one with the higher energy must contain more particles (per gram). 1Therefore, there are more particles in the water than in the iron. 1Accept equivalent answers.
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EXTENSIONQuestion Answer Mark
4 a The larger snake contains more particles 1so must gain more energy to reach the same temperature as the smaller 1snake. Accept equivalent answers.
b It has not warmed up in the morning so has not the energy to attack. 1Accept equivalent answers.
c Flattening out increases their surface area 1so they can absorb the sun’s energy faster. 1
5 a i Crew A. 1
ii The larger mass of wood contains the most energy 1so it needs more water to absorb the energy. 1
b Heat 1
6 a i Y 1
ii It warms a much larger volume/amount of water to a higher temperature 1than the others.
b i The water temperature/it would be lower. 1
ii The same amount of energy is being absorbed by fewer water particles 1so the average energy per particle is greater. 1
1 The missing word sequence from the left is: freezing; liquid; 4boiling; condensing
2 a Sensible scale. 1Axes labelled. 1Single line drawn. 1Clearly shows ‘flat spot’. 1Award a maximum of 2 marks for a bar graph.
b It is freezing/solidifying/turning into a solid. 1
c They are closer together/in a regular pattern/all touching/not moving around. 2Award 2 marks for two suggestions from the list given above.
Total for Help 11
COREQuestion Answer Mark
3 a Graph is the reverse of the one plotted for Question 2a. 2Award 1 mark for the overall shape and 1 mark for a flat spot at 24°C.
b They would:separate from each other. 1move around very fast. 1
c It is separating/breaking apart the particles from each other. 1
Total for Core 5
EXTENSION
Question Answer Mark
4 a One that can go in both directions, 1such as a liquid becoming a gas, then condensing back to a liquid as it cools. 1Accept other correct examples.
b i Graph must have: General upward trending line from left to right. 1A flat spot at 0 °C. 1Another flat spot at 100°C. 1
ii Answer must contain:a reference to the generally increasing energy of the particles raising 1the temperature.an indication that, at the two flat spots, the forces of attraction are being 1broken rather than the substance merely being warmed up.
c When steam burns the skin absorbs all the energy that has gone into 1separating the particles,as well as the energy that raised it to 100°C. 1With boiling water, only the energy that raised its temperature to 100°C 1is absorbedwhich is significantly less. 1
d As the steam condenses, forces of attraction between the molecules develop. 1These hold the molecules closer together in the liquid. 1
1 a Sentence must contain reference to the metal being a good conductor of heat. 1
b Sentence must contain ref to plastic being a poor conductor/good insulator. 1
c Sentence must contain reference to the heat transferring from the metal to 1the water quickly.
d Sentence must contain reference to the metal being a good conductor of heat. 1
2 a i The thermometer that reached the highest temperature was the one above the 1solid copper box because solids conduct heat faster than liquids or gases.Underscore shows the pupil response.
ii The thermometer above the air-filled box hardly warmed up at all because 1air is a very poor conductor of heat. Underscore shows the pupil response.
b Normal double-glazing helps to keep houses warm because the air between 1the glass panes does not conduct heat very well/is a good insulator.Underscore shows the pupil response.
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COREQuestion Answer Mark
3 a There are air pockets inside the fibre roll 1which do not conduct heat well 1and fibre is also a poor thermal conductor. 1
b The polystyrene foam is a poor conductor of heat. Accept ref to air pockets in foam. 1
4 a Copper. 1
b Glass. 1
c Thermal energy is conducted when high energy particles collide with lower 1energy ones next to them passing on some of their energy. 1Particles in a solid are much closer together than those in gases 1so they collide with each other much more often. 1
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EXTENSIONQuestion Answer Mark
5 a Heat energy in the vibrating coffee particles is transferred to the metal 1when the coffee particles collide with the metal particles.This makes the spoon particles vibrate more 1so they knock into the next ones up the spoon, transferring some of the 1thermal energy.This continues up the spoon to your hand, which detects the thermal energy. 1
b There is a vacuum between the sun and the earth 1and vacuums do not conduct heat 1because there are no particles to transfer it. 1
c i There are many more particles in the water than in the horseshoe 1so the thermal energy in the shoe is much more spread out in the water. 1
ii Air is a poorer thermal conductor than water 1so the thermal energy spreads out much more slowly. 1
1 a Seven words to be found; see pupil sheet. Deduct 1 mark for each word not found. 5
b Conduction. 1
c Convection 1current. 1
d Thermal. 1
e Temperature. 1
Total for Help 10
CORE
Question Answer Mark
2 a Sentences must include reference to:hot air above the radiator rising and spreading 1cool air in the room falling and replacing the air near the radiator 1
b Towns produce heat. 1The air over a town is warmed by the heat 1so convection currents are set up 1which rise upwards from the town. 1The convection currents carry the glider up. 1
c Diagram should contain the following arrows:Upward arrow(s) over the land. 1Downward arrow(s) over the sea. 1Arrow showing wind moving from the sea towards the land at sea level. 1
Total for Core 10
EXTENSION
Question Answer Mark
3 a The burners warm the air inside the balloon. 1This lowers its density compared with the air outside the balloon. 1
b The density must be kept the same 1or the balloon will rise or fall. 1
c The hole provides a route for the warm air to escape from the balloon 1so the air inside cools more quickly and the balloon descends faster. 1
d The burner heats the air inside the balloon. 1This makes the air particles inside the balloon move faster 1so they become less dense 1and take up more space. 1The balloon must expand to provide the extra space needed by the air particles. 1
4 The fire is heating the air above it. 1This creates strong convection currents rising upward. 1The currents carry the smoke/soot particles as they rise. 1
6 These sentences are about changes of state when a substance is heated. Cross out the wrong words.
a When a solid is heated, its temperature rises/falls/stays constant. At its meltingpoint it turns to a liquid/gas. During melting, the temperature rises/falls/staysconstant while the particles break apart/join together. When all the substanceis liquid the temperature rises/falls/stays constant.
b A liquid turns to a gas at its freezing point/melting point/boiling point.During boiling, the temperature rises/falls/stays constant while the particlesbreak apart/join together. The particles are free to move about in the gas.
7 Here is a list of thermal conductors and insulators.Underline the conductors. Circle the insulators.
aluminium polystyrene copper rubber
wood water air silver brass
8 Loft insulation is made from a material that has lots of pockets of trapped air.
It works because air is a good insulator. Without loft insulation, the roof space
is full of air. Why does this not keep the heat in?
9 The diagram shows water being gently heated. Complete the description of what happens.
When the water is heated, it and so becomes less
. This causes the water to rise. Cooler water falls
because it is more dense. So currents are
set up in the water. In time, it will all be heated to the same
. Convection also happens in .
10 How does heat reach us from the Sun, by conduction, convection
or infrared radiation?
11 Which is the best explanation for when evaporation occurs?Circle the correct letter.
A A liquid reaches its boiling point.
B The most energetic molecules escape from the liquid.
C Slow moving molecules escape from the surface of the liquid.
6 These sentences are about changes of state when a substance is heated. Cross out the wrong words.
a When a solid is heated, its temperature rises/falls/stays constant. At its meltingpoint it turns to a liquid/gas. During melting, the temperature rises/falls/staysconstant while the particles break apart/join together. When all the substanceis liquid the temperature rises/falls/stays constant.
b A liquid turns to a gas at its freezing point/melting point/boiling point.During boiling, the temperature rises/falls/stays constant while the particlesbreak apart/join together. The particles are free to move about in the gas.
7 Here is a list of thermal conductors and insulators.Underline the conductors. Circle the insulators.
aluminium polystyrene copper rubber
wood water air silver brass
8 Loft insulation is made from a material that has lots of pockets of trapped air.
It works because air is a good insulator. Without loft insulation, the roof space
is full of air. Why does this not keep the heat in?
9 The diagram shows water being gently heated.
Complete the description of what happens.
When the water is heated, it and so becomes less
. This causes the water to rise. Cooler water falls
because it is more dense. So currents are
set up in the water. In time, it will all be heated to the same
. Convection also happens in .
10 How does heat reach us from the Sun, by conduction, convection
or infrared radiation?
11 Which is the best explanation for when evaporation occurs? Circle the correct letter.
A A liquid reaches its boiling point.
B The most energetic molecules escape from the liquid.
C Slow moving molecules escape from the surface of the liquid.
7 Rachel investigated how insulation could reduce the flow of thermal energy in a house. She built two model houses from cardboard boxes. One was insulated withloft and wall insulation, the other was not. Rachel used a sheet of plastic for thewindows and doors for both houses. Electric light bulbs were used to heat the houses.A temperature sensor measured the temperature change in the houses.
This is the graph made by the two sensors in the model houses.
a Which graph line, A or B, would be the house with the greatesttemperature rise? 1 mark
b Would the house with the greatest temperature rise be thehouse with the insulation? 1 mark
c Why did Rachel test one house with no insulation? 1 mark
d Rachel could also have made a house with just loft insulation.Which graph line, A, B, C or D, would show this house? 1 mark
e Why was Rachel careful to seal all the holes in the boxes? 1 mark
4 Explain why the rod below expands when it is heated. 2 marks
5 In an experiment, the apparatus was set up asshown in the diagram.
a What would happen to the air particles inthe flask as it was heated? 1 mark
b What would happen to the air in theflask as it cooled? 1 mark
c What would happen to the water in the beaker as the flask cooled? 1 mark
6 Some ice cubes were placed in a beaker of water. The beaker was then heated with a Bunsen burner. The temperature of the water was recorded every two minutes. The graph of the results is shown below.
a Explain why the temperature of the ice remains at 0 °C forseveral minutes even though the ice is being heated up. 1 mark
b Explain the change from water to steam in terms of the forcesbetween the particles. 1 mark
7 What is the main method of heat transfer involved in each ofthe following?
a heat travelling from the Sun to Earth 1 mark
b the air in a room heated by an electric heater 1 mark
c heat travelling through a mat between a Bunsen burner andthe bench below 1 mark
8 Rachel investigated how insulation could reduce the flow of thermalenergy in a house. She built two model houses from cardboardboxes. One was insulated with loft and wall insulation, the otherwas not. Rachel used a sheet of plastic for the windows and doorsfor both houses. Electric light bulbs were used to heat the houses.A temperature sensor measured the temperature change in the houses.
a Why did Rachel test one house with no insulation? 1 mark
b On the graph, lines A and B are from the sensors in Rachel’s model houses.
Rachel could also have made a house with just loft insulation. Which graph line, A, B, C or D, would show this house? 1 mark
c Why was Rachel careful to seal all the holes in the boxes? 1 mark
d Rachel says that the more insulation the less thermal energy is lost. Which results support this conclusion? 1 mark
e Rachel says that using the temperature sensor made the resultsmuch more reliable than if she had used a thermometer. Whatwas her reason for saying this? 1 mark
I1 What temperature?Green1 There are 100°C between ... freezing water and
boiling water.Things feel hot because ... thermal energy flowsinto our skin.Water freezes and melts ... at 0°C.The scientific word for heat is ... thermal energy.Things feel cold because ... thermal energy flowsout of our skin.Water boils and condenses ... at 100°C.
2 a, b, c15400000000°C: centre of the Sun100°C: boiling point of water79°C: boiling point of ethanol37°C: temperature of the human body4°C: fridge temperature0°C: freezing point of water−22°C: freezer temperature−235°C: Triton, moon of Neptune
Reda i The glass would melt.
ii 59°Ciii 42°C
b There was less thermal (heat) energy in the hallthen there was in the living room.
1 The Celsius scale is divided into 100 divisions.Each division marks one degree of temperaturebetween the freezing point and boiling point ofwater.
2 We need thermometers to show us the amountof thermal energy present.
3 There is no such thing as cold. Cold simplymeans less thermal energy than somewhere else.
4 Individual answers.
I2 Temperature and energyGreena 80°Cb Heating the full kettle to 100°C.c i The part-full kettle.
ii The full kettle.1 a Temperature is measured in degrees Celsius
(°C). b The energy per particle is the temperature.c It takes more energy to increase the
temperature if there are more particles.2 a 100cm3. There are more particles so the total
energy is greater.b 10cm3 at 90°C. The particles have more
energy at 90°C than at 30°C.c 10000g of iron at 20°C. There are a great
many more particles. So even though eachparticle has less energy, the total energy fromall these particles is greater.
Reda 80°Cb Three times as much energy.c i 40p
ii 200pd i The part-full kettle.
ii The full kettle.e i 1kg of lead at 400°C.
ii 1g of ice at −10°C.iii 100g of ice at −10°C.
1 The gate contains many more particles than theiron poker. Although each particle in the pokerhas more energy than each particle of the gate,there are so many more particles in the gate thatits total energy is greater.
2 i 8cm3 iron at 1000°C.ii Each ‘child had more money’ in the second
experiment. Each particle had more energyat 84°C than those at 28°C. So the ‘totalamount of money’, the total energy in thesecond experiment, was greater.
I3 Bigger and smallerGreena The gaps allow the tracks to expand without
bending out of shape.b Heating makes the particles vibrate more so they
take up more space.c Cooling makes the particles vibrate less so they
take up less space.d i contract
ii Closer together.1 Solids, gases and liquids all expand when they
are heated. Solids (or liquids) and liquids (orsolids) expand because the particles vibratemore and take up more space. Gases expandbecause the particles get further apart.
2 Individual answers.3 The metal ruler contracts on a cold day so the
divisions are closer together than when the ruleris hotter and the spaces between the divisionsare greater.
Reda The gaps allow the concrete sections to expand
without crushing into each other in hot weather.b Particles vibrate more in a hotter solid than in a
colder solid.c The particles in a cooler liquid vibrate less so
they take up less space.d When the balloon cools, the air particles inside
move more slowly and hit the insides of theballoon with less force, so the balloon isn’tstretched as much as before it was cooled.
1 a The rivet contracts.b The metal plates are pulled tightly together.
2 a Gases have fewer particles in a certainvolume than do either a liquid or solid.
b When the temperature of a solid or liquidincreases, the particles vibrate more and takeup more space. Therefore there will be fewerparticles within a certain space, so thedensity decreases.
3 The metal jam-jar lid will expand more than theglass jar when heated. Therefore the lid willcome away from the glass more easily.
I4 All changeGreena i An electric heater.
ii A temperature probe.b Solid, liquid and gas.c The temperature increases.d Breaking the particles apart from each other.1 To melt or boil something ... you have to put
energy in.When you give the particles more energy ... thetemperature goes up.When the energy is breaking the particles apartduring melting or boiling ... the temperaturedoesn’t go up.
2 a To condense or freeze something you haveto remove energy from it.
b When you take energy away from theparticles the temperature decreases.
c You don’t get a drop in temperature duringfreezing or condensation.
Reda i The particles vibrate faster.
ii The energy going into the ice is used to breakthe particles apart from each other.
b During boiling, the energy is used to break theforces of attraction between the particles in theliquid.
c
d i Any temperature above 100°C.ii 100°C
1 a The energy goes into making the particlesvibrate more.
b The energy is used to break the forces ofattraction between the particles of water.
2 a i Label pointing to 0°C.ii Label pointing to 100°C.
b i Label pointing to the part of the curvebelow 0°C.
ii Label pointing to the rising straight linebetween 0°C and 100°C.
iii Label pointing to the flat part of thegraph at 100°C.
iv Label pointing to the flat bit of the graphbetween two and four minutes at 0°C.
c Stars placed at both flat horizontal parts ofthe graph, at the 0°C and 100°C sections.
3 As the water in the freezer becomes colderenergy is removed from the water, thetemperature decreases and the waterparticles vibrate less. When the temperaturereaches 0°C the energy being removed causesnew forces of attraction to be made and thetemperature remains constant. When all of thewater has become solid, the energy beingremoved causes the temperature to fall to −20°Cand the vibration of each particle becomesless.
I5 ConductionGreena Individual answers.b i The particles.
ii The energy.iii The particles (‘children’) are held together
in fixed places by the forces of attraction.c When all the particles reach room temperature.d metale plastic1 Conduction is when energy is passed from
particle to particle. The particles need to betouching. The energy moves from the hotterparts of the material to the cooler parts of thematerial.
2 Aluminium, water, plastic, air, vacuum.3 a The metal of the skewer is a very good
conductor and conducts the heat quicklyinto the centre of the kebab.
b Wooden skewers would not work becausewood is a good insulator.
Reda The surroundings contain many particles, so each
particles loses just a small amount of energy.b Conduction stops when each particle has the
same energy and is at the same temperature.c i six
ii In the liquid there are different numbers ofparticles touching other particles, from one
Temperaturein °C
Time in minutes1050
0
50
100
150
200
Steam beginsto condense toliquid water.
Water is cooled.
Steam cooling.All of the steamhas condensedto water.
to six. In the gas there are only individualparticles, with no others touching them. Inthe vacuum there are no particles to hiteach other so there can be no transfer ofthermal energy.
iii Solids conduct thermal energy best becausethey are touching the most other particlesand can pass their energy on easily.
d Gas pockets contain very few particles, which donot touch each other, so energy is conductedvery slowly.
1 a aluminium, graphite, water, plastic, airb Solids are better conductors than liquids or
gases. Metals are the best conductors, soaluminium comes first with graphite second.Water is a liquid so it conducts better thangases. Plastic contains air pockets and air is agood insulator.
c Last. There are no particles to hit each otherso there can be no transfer of thermal energyby conduction.
2 a The metal of the skewer is a very goodconductor and conducts the heat quicklyinto the centre of the kebab.
b Wooden skewers would not work becausewood is a good insulator.
3 Conduction causes thermal energy to betransferred from hotter objects to cooler objects.The heated end of the solid has particles withlarge vibrations. As they vibrate they hit particlesnext to them and energy is passed on. Thishappens from each hotter particle to its coolerneighbouring particle. This continues until eachparticle has an equal amount of energy.
I6 ConvectionGreena The particles in a solid do not flow or move
around.b twoc The purple dye moves upwards.d All the water would be evenly coloured purple.e The table on the right with more money.f The particles are in fixed positions and cannot
move about.1 Thermal energy can be transferred by
convection. Convection happens in gases (orliquids) and liquids (or gases) but not insolids. Convection currents happen when thereis a temperature difference. Hotter liquid orgas rises and cooler liquid or gas falls.
2 Individual answers as: the heater on one side ofthe room heats the air above it. This hotter airbegins to rise and cooler air falls to replace itover the heater. The cool air is heated by theheater and rises again and the process is
repeated over and over again, causing risingconvection currents of air. As theconvection currents continue, the warm airand cooler air mix.
3 The two tables represent two different placeswhich hold different amounts of energy –i.e. they have different temperatures. Thechildren are the particles that move to takemoney (energy) from the hotter place, the tablewith more money, to the other table with lessmoney, which is cooler. This happens inconvection. But in conduction the particles(children) are not able to move. The particlesvibrate and knock into each other and passon their energy from the hotter, morevibrating particles to the cooler, less vibratingparticles.
Reda The particles in a solid do not flow or move
around.b The air inside the balloon is hotter than the air
outside the balloon. Because the air inside theballoon is hotter, it is less dense than the airoutside. Less dense materials float above moredense materials. The hot air rises, like a corkbobbing up through water.
c The purple dye would have been mixed with thewater after three minutes.
d There are fewer particles of the hotter liquidthan the colder liquid in the same volume.
1 As the air in the balloon cools, the particlesvibrate more slowly and there are more particlesin a certain volume than there were before. Theair becomes more dense. Materials which aremore dense than the materials around them willsink, so the balloon falls.
2 Suitable diagram showing convection currentsof hot air rising from the land and cool sea aircoming inland to take the place of the rising hotair.
3 The heater on one side of the room heats the airabove it. This hotter air begins to rise and coolerair falls to replace it over the heater. The cool airis heated by the heater and rises again and theprocess is repeated over and over again, causingrising convection currents of air. As theconvection currents continue, the warm air andcooler air mix.
4 Two tables represent two different places thathold different amounts of energy – i.e. theyhave different temperatures. The children arethe particles which move to take money(energy) from the hotter place, the table withmore money, to the other table with less money,which is cooler. This happens until the moneypiles on both tables are the same. Thisrepresents a complete mixing of the fluid.
I7 Evaporation, radiationGreena They break away from the liquid to become a
gas and they gain energy.b i From our bodies.
ii From the tea in the cup.c i There is a vacuum around the Earth.
ii radiationd i The children with the money.
ii The children catching the money.iii The money being thrown.
1 Energy is transferred away from liquids byevaporation. The particles with the mostenergy leave the liquid and become part of agas. Radiation energy is like light. It cantravel through many materials and across avacuum. It transfers thermal energy from ahotter object to a cooler object.
2 radiation – green arrows, convection – bluearrows, evaporation – purple arrows,conduction – red arrows
Reda i The money. ii The children.
iii The number of children.iv The children passing through the turnstile.
b i The Earth is surrounded by a vacuum. Therecan be no conduction or convection wherethere are no particles to move.
ii radiationc i The middle of the room represents empty
space or a vacuum.ii The hot object is represented by the
children with coins. The cooler object isrepresented by the children receiving thecoins. The infrared radiation is representedby the coins themselves.
1 Individual answers, such as: when a personsweats, water particles leave the skin byevaporation. When they leave they becomegas particles which are faster moving andhave more energy. This energy is takenfrom the skin, so the temperature of theskin falls.
2 radiation – green arrows, convection – bluearrows, evaporation – purple arrows,conduction – red arrows
3 In conduction, the children are in fixedpositions; each child passes money to the childalongside. In convection the children moveabout and pass money from one table that haslots of money to the table with no money untilthe tables have the same amounts of money. Inradiation there are two groups of childrenseparated by an empty space. One group withlots of money throws money across the gapbetween them to the group with no money.
I8 Explaining the resultsGreena Ellen. There was a pattern.b Increasing the mass increased the amount of
energy needed.c Aluminium needs more energy than copper,
which needs more energy than tin.d 720kJ (±10kJ)e Sean. They would all lose energy. Such a big
difference is not likely from cooling.f No. They still got different results.g Yes. Keeping all the heat in still gave different
amounts of heat needed for the different metals.1 a The particles in a warmer solid vibrate more.
b Yes. The graph shows that for a certainamount of energy input, as Mr Smith’s 300kJ,only 83g of aluminium was heated by 40°Cwhereas 346g of tin was heated by that sameamount.
2 a copperb aluminiumc Yes. It can be seen on the graph that for a
certain amount of each metal it takes mostenergy to heat up aluminium by 40°C, lessenergy for copper and the least energy for tin.
Reda Individual answers.b The greater the mass of the block, the more
energy is needed to raise the temperature of theblock.
c The less dense the meat, the more energy isneeded to raise the temperature of a certainmass of the metal.
d i 310kJ (±10kJ)ii 720kJ (±10kJ)
iii 185kJ (±10kJ)e i 194g (±10g)
ii 83g (±10g)iii 346g (±10g)
f 740kJ (± 20kJ)g The input variables are the type of gas, the
volume of gas inside and the total mass of theballoon. The outcome variables are the balloon’srise and fall.
h The greater the volume of some gases put intothe balloons, the more they will rise. Forexample, the balloon with 1000cm3 of heliumsank but the balloon with 4500cm3 of heliumrose. The balloon with 1000cm3 of neon sankbut the balloon with 9500cm3 of neon rose. For all of the other balloons that didn’t havehelium or neon in them, it didn’t matter howmuch gas was put into them. They all sank.
i The greater the mass of the balloons withcertain gases inside, the more they rose. Forexample, the balloon with mass 3.16g filled
with helium sank, but the balloon of mass 3.72gfilled with helium rose, as did the one of mass4.12g. Similarly, the balloon of mass 3.18g filledwith neon sank but the balloon of mass 10.68gfilled with neon rose.
j Individual answers. Pupils choose a balloon witheither helium or neon which rose to use as theirexample. They add to the balloon a mass tomake the density of the balloon, with addedmass, equal to 0.00115g/cm3.
k 0.00083g/cm3
l 0.00115g/cm3
m 1.455g1 The balloons that contained air were more
dense than the air around them because of the
mass of the rubber in each balloon adding to themass of the air inside it. So the total mass of theballoon was greater than the mass of air whichit contained.
2 a 2609cm3
b The volume has to be greater because youneed to float the mass of the hydrogen aswell as the mass of the balloon.
c Individual answers similar to: when you heata certain amount of air the particles movefaster and become further apart and itsvolume increases. Since the mass of the airremains the same, the density of the air isless than the surrounding air and the hot-airballoon rises.
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