Competency 1 Scientific Method and Graphing

Important Safety Symbols

Biohazard: organisms and other biological materials may be harmful to humans

Radiation: radioactive material nearby

Important Safety Symbols

Potentially harmful fumes

Sharp object

Important Safety Rules

Never smell anything directly from a test tube. Point test tube away face and gently waft gas toward nose.

Important Safety Rules

Wash your hands and clean up your lab station after the experiment.

When in doubt, just TELL THE TEACHER! Broken glassware

or equipment Spills Injury Contact with

chemical on skin or in eyes

Lab Equipment

Graduated Cylinder Used to measure precise

volumes of a liquid. To correctly measure

volume, look at the bottom of the curved line called the meniscus.

Make sure you are reading it at eye level!

How many mL are in this graduated cylinder?

Answer: 43.5

Lab Equipment

Triple Beam Balance Measures the mass of

objects

Lab Equipment

Triple Beam Balance How to read:

What is the total mass of of this object?

500 + 40 + 5.2 = 545.2

Lab Equipment

Beaker

Both can be used for stirring, mixing, measuring and heating liquids

Flask

Lab Equipment

Pipette Used for transferring

liquids and/or measuring small amounts of liquids (a few mL).

Bunsen burner Used for heating.

1. Make an Observation

2. Define the Problem

3. Research the Problem

4. State the Hypothesis

5. Experiment to test Hypothesis

6. Collect and Record Data

7. Analyze Data

8. Draw Conclusions

9. Determine Limitations

10. Report Results

Scientific MethodListing the Steps

Ask Question

Do BackgroundResearch

ConstructHypothesis

Test with anExperiment

Analyze ResultsDraw Conclusion

Think!Try Again

Report Results

Hypothesis is True Hypothesis is Falseor Partially True

A hypothesis is: An educated guess, trial answer,

possible solution, prediction Must be a statement

(usually in “If…then” format) Must be testable or measurable Is based on your research and previous

experience

Scientific Method Creating a Hypothesis

Step 1: Define the problem. Example: Does the temperature of water

affect the amount of sugar that will dissolve in it?

Step 2: Make a prediction, a.k.a. hypothesis. If the temperature of water is increased,

then the amount of sugar that can be dissolved in it will increase.

Scientific Method Creating a Hypothesis

You must make a prediction that is measurable by an experiment.

If you are not predicting a measurable outcome, there is no way to test the hypothesis.

A hypothesis must be testable!

Use a Controlled Experiment An experiment that tests only one factor at a

time by using a comparison of a control group and an experimental group.

Control Group The group that the scientist changes nothing

in. The Control group is used for comparison. Experimental Group

The group that the scientist has changed something. It is the variable in the experiment where you want to see how this condition affects something.

How do you test a hypothesis?Experimenting

Example:Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks.

What is the control group? The plants in the sunlit window Why? Plants are naturally found in areas with at

least some sunlight. Nothing was changed about their normal habitat regarding sunlight.

Setting up an Experiment:Control Group

Example:Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks.

What is the experimental group? The plants in the dark closet. Why? Photosynthetic plants are not normally found

in completely dark environments. The scientist wants to see how this change will affect this group of plants.

Setting up an Experiment:Control Group

A variable is something that can be changed. In an experiment it is a factor that is different from one

group to another. Controlled variables– (constants) All the variables that

remain constant Independent variable– (manipulated variable) factor that

is purposely changed Dependent variable– (responding variable) factor that

may change because of independent variable; what scientist wants to observe

Setting up an Experiment:What is a variable?

Example:Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks.

What is the independent variable? Light—the scientist purposely changes the amount

of light available to the plants.

Independent Variable

Example:Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks.

What is the dependent variable? Plant growth—the scientist will observe and measure

how much the plants grow as a result of the light and dark conditions

Dependent Variable

Example:Six bean plants are to be tested to see what happens if light is taken away. The all have the same type of container, the same amount of soil, and they will receive the same amount of water. Three will be placed in a sunlit window and 3 will be placed in a dark closet for 2 weeks.

What are the constants? Same container, amount of soil, amount of water

In a controlled experiment, you must keep everything the same except one variable!

Controlled Variables (Constants)

Results of an experiment are not reliable if the experiment is not conducted properly.

When conducting an experiment, always make sure to: Complete at least 3 trials Only change one variable at a time Have a control group to compare with

experimental group

Experiments must be VALID

James wondered if music had an effect on

plant growth. He set up an experiment where

25 bean plants were placed in a chamber

where music was played and 25 bean plants

were placed in an identical chamber where

music was not played. He placed one

chamber outside in the summer heat and one

chamber he kept inside his house. He gave all

plants the same amount of fertilizer, soil, and

water. At the end of two weeks plant height

was measured.

What is wrong with this experiment?

James wondered if music had an effect on

plant growth. He set up an experiment where

25 bean plants were placed in a chamber

where music was played and 25 bean plants

were placed in an identical chamber where

music was not played. He placed one

chamber outside in the summer heat and

one chamber he kept inside his house.

He gave all plants the same amount of

fertilizer, soil, and water. At the end of two

weeks plant height was measured.

What is wrong with this experiment?

A study was done to see if leaves added to soil had an effect on tomato production. Tomato plants were grown in four large tubs. Each tub had the same kind and amount of soil. One tub had 15 kg of rotted leaves mixed in the soil and the second had 10 kg. A third tub had 5 kg and the fourth had no leaves added. Each tub was kept in the sun and watered the same amount. The number of kilograms of tomatoes produced in each tub was recorded.

What is the control group? What is the experimental group? Independent variable: Dependent variable: Control variables:

Identify the Variables

Tub with no added leaves.All tubs with added

leaves.Different kg of leaves added to each tubKg of tomatoes

producedSame size tub, same type and amount of soil, same amount of sunlight and water

Bart believes that mice exposed to microwaves will become extra strong. He decides to perform this experiment by placing 10 mice in a microwave for 10 seconds. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. He found that 8 out of 10 of the microwaved mice were able to push the block away. 7 out of 10 of the non-microwaved mice were able to do the same. He recorded how many mice could push the block away.

What is the control group? What is the experimental group? Independent variable: Dependent variable: Control variables:

Identify the Variables

10 non-microwaved mice 10 microwaved mice

microwave

Number of mice that can push the blockNumber of mice kept same

between groups, same block of wood

Graphs help us visualize numerical data. There are 3 different types of graphs:

Bar graphs Pie graphs Line graphs

Graphing in Science

A bar graph is used to show relationships between groups.

The two items being compared do not need to affect each other.

It's a fast way to show big differences. Notice how easy it is to read a bar graph.

Bar Graph

Chocolate Milk Sold

53

72

112

33

76

0

20

40

60

80

100

120

Monday Tuesday Wednesday Thursday Friday

Day

Am

ount

Sol

d

Monday TuesdayWednesday ThursdayFriday

• Question:On what day was the most chocolate milk sold?

• Answer:Wednesday

A circle graph is used to show how a part of something relates to the whole.

This kind of graph is needed to show percentages effectively.

Question: Which day was the least chocolate milk sold?

Answer: Thursday

Circle Graph or Pie Graph

Chocolate Milk Sold

Monday

Tuesday

Wednesday

Thursday

Friday

A line graph is used to show change over time.

It's clear to see how things are going by the rises and falls a line graph shows.

Line Graph

Chocolate MI lk Sold

0

20

40

60

80

100

120

Monday Tuesday Wednesday Thursday Friday

Day

Am

ount

Sol

d

Chocolate

Question: On which day was there a drop in milk sales?

Answer: Thursday

Line Graph

Chocolate MI lk Sold

0

20

40

60

80

100

120

Monday Tuesday Wednesday Thursday Friday

Day

Am

ount

Sol

d

Chocolate

Identify the Variables Number and label each axis Plot the points Draw the graph Give your graph a title

Graphing Experimental Results

Graphing Experimental Results:Identify the Variables

To move image to the left, move stage to the right. To move image to the right, move stage to the left. OPPOSITE!

Your microscope has 3 magnifications: Low, Medium, and High. Each objective will have written the magnification. In addition to this, the ocular lens (eyepiece) has a magnification. The total magnification is the ocular x objective

Microscopes

Magnification

Ocular Lens Total Magnificati

on

Low 4x 10x 40x

Medium 10x 10x 100x

High 40x 10x 400x