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 Science Curriculum Standards

Proficient Level

Secondary

“Fair Test”

Workshop8: 10/5/2011

4:00 - 4:05 PM Welcome

4:05 - 4:15 PM

Starter on Fair test

4:15 - 5:30 PM Fair test

5:30 - 6:00 PM Can we implement the fair test in students’ exams?

6:00 - 6:15 PM Prayer Break

6:15 - 7:15 PM How can you help your students to fair test?

7:15 - 7: 30 PM

Survey and Feed back

AGENDA

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STARTERAhmed and Ali are investigating how electrical resistance of wires changes with length. Unfortunately both of them let the current get too high for shorter wires, which increases the temperature drastically. Since temperature affects resistance (in addition to the length), it is not a fair test. Think:1. What are the mistakes students did it in this

experiment?2. What could we do to make it good experiment (fair

test)3. Identify the independent and dependent variables

in their investigation.

Conducting a Fair Test

Conducting a Fair Test

How Science Works

How Science Works

What is a Fair Test?What is a Fair Test?

“A fair test is where you ensure that results are due to the effect of the independent variable on the dependent

variable and to no other factors.”

“You achieve this by ensuring that all the variablesother than the independent variable are

kept constant or controlled.”

What is a fair test?

An investigation where only one factor is changed while all others are kept the same (controlled).

This way, the changes are due only to the thing we want to test

e.g. if testing the effect of amount of light on growth of seedlings, keep everything else the same e.g. type of soil, amount of water, temperature, length of time grown etc.

Variables The things that can change in an

experiment are called variables.

e.g. in the seedling experiment, variables were amount of light, amount of water, temperature, soil type….

There are different types of variables in an investigation:

Independent variable: (What I change) the thing that is changed on purpose

Dependent variable: (What I observe / measure) the thing that is measured

Controlled variables: (What I keep the same) all other changeable factors that must be kept the same to ensure a fair test

Variables

The following apparatus is used to investigate the effect of glucose concentration on the rate of yeast respiration.Glucose concentration is the independent variable, and the volume of gas produced is the dependent variable...

ExampleExample

Identify the control variables that you would need to keep constant during the experiment, to ensure a fair test.

Identifying Control VariablesIdentifying Control Variables

Move on to the next slide to show the variables…

The age and species of the yeast

The temperature of the reactants

The mass of yeast

The volume of glucose solution

“To be sure that changes in the volume of carbon dioxide produced are due to changes in glucose concentrations, you

would have to ensure that the followingcontrol variables were kept constant…”

Identifying Control VariablesIdentifying Control Variables

Identifying a Fair TestIdentifying a Fair TestFor these investigations, identify the experiment which would give a fair test…

Can we implement

the fair test in

students’ exams!!?

A fair testTest B, 5a Bean seeds

In this question Aisha has described how she will make an investigation fair.

Pupils need a good understanding of why a test needs to be fair in order to recognise and explain if the factors are important or not.

In part 5b, most pupils recognised that the colour of the watering can doesn’t matter.

However, in this part, 5a, pupils have more difficulty recognising why using the same type of soil is important.

Level 3Sc1/2d

Which responses are correct?

A. One type of soil could be rocky and the other plain mud with toxins

B. Because she is using the same thing on everything

C. Because she should only change the type of bean seed she grows

D. Some soil might have more nutrients than a different type of soil

E. Because you need to make it fair in a test

F. If she uses different soils, one might be better than another

G. If you use different types of soil the beans might grow quicker or slower

H. Some seeds may only grow in a certain soil

I. Some soils have less pH than others

J. If you use a different soil you won’t get a fair test

K. She is trying to find out which seed germinates more quickly, not the best soilB, E, J = Wrong A, D, F, I = Allowable C, G, H K = Correct

© Qualifications and Curriculum Authority, 2006.

Identifying the variables to make a fair test Test B, 9b Making

bread

In this question pupils are given all the variables in a test.

They are required to identify which ones should be kept the same in each mixture, and which is the variable being changed.

Level 4

Sc1/2d

© Qualifications and Curriculum Authority, 2006.

Identifying the variables to make a fair test Test B, 9b Making

bread

In this question pupils are given all the variables in a test.

They are required to identify which ones should be kept the same in each mixture, and which is the variable being changed.

Level 4

Sc1/2d

How can you help

students?

Generate Ideas

Change

Measure/observe

Which variable might affect…

What will be our

evidence?

c

Let’s make a question

The variable I will change is..

The variable I will measure/observe is

m

c

These variables I will keep the same

ccc

c c

Making a prediction

the

when I c

m

I think that…

What will happen to

because…

How much data do I need?

m

c

How many

I will have

I will take

Why might you want to measure/observe what happens more

than once?

To make your data

more reliable

Table of Results

changec m

Table of Results

changec m

*

When you draw up a table of your results,the independent variable goes in the first column, like this:

Tables

If you take several readings of the dependent variable, then you can calculate the mean (average)

Then your results will be more reliable.

Making a graph

m

c

Interpreting graphs

m

c

Key questions•Which is the highest reading?•Which is the lowest reading?•Do all the readings increase?•Are there any unusual readings?

Drawing conclusions

When I

m

c

What happened to

Key Questions•What happened and why?•Is this what I thought would happen?•Has this proved or disproved a some of my scientific understanding?

Examplesof investigation

Take a simple context such as bouncing a ball, or dissolving some sugar in water.

Look at your lists and think about the following: Which factors are suitable for being measured (the

dependent variable)?

Are there any variables that are irrelevant and unlikely to affect the outcome of the investigation?

Out of the remaining variables, only one should be changed in an investigation (the independent variable) and all the others should be kept the same.

Write down a question using these variables that you could investigate.

Example of question to investigate – bouncing ball

Type of ball Weight of ball Height from which ball is dropped Size of ballSurface on which ball is dropped Indoors or outside How high the ball bounces How the ball is droppedNumber of times the ball bouncesHow long the ball continues to bounce

How many times will a ball bounce on different surfaces?

dependent variable independent variable

Which of the variables need to be kept the same for this investigation?

Example of question to investigate – dissolving sugarAmount of sugar Type of liquidType of sugar Material of beakSize of beakerHow long it takes to dissolveAmount of waterStirring the mixtureTemperature of water Thermometer

How long will it take to dissolve different types of sugar?

dependent variable independent variable

Which of the variables need to be kept the same in this investigation?

Your Turn: Planning a Fair Test

Biology:•Investigate the tar content of different brands of cigarette.•Investigate the effect of concentrations of sulfur dioxide on growing plants.•Investigate the effect of exercise on the heart rates of people’s size.•Investigate the rate of osmosis between solutions of different concentration.•Investigate the effect of concentrations of sulfur dioxide on growing plants.

Your Turn: Planning a Fair Test

Physics•Do investigation to show that the time taken by an object to drop is independent of its mass under conditions of negligible air resistance.•Do investigation to measure the power output of a muscle under varying conditions.•Do investigation to compare the insulating properties of different roof materials and structures.•Do investigation to study the factors effecting on the resistance of a wire

Your Turn: Planning a Fair Test

Chemistry:•Investigate the effect of factors affecting rates of reaction.

•Do investigation to compare the energy output from a blue and a yellow Bunsen flame.

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Do science investigation in your classroom.

Bring the daily lesson plan. Evidence of students work. The reflection on your lesson.

Home Work

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