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Primary Science · Year 5Chapter 1 · Working scientifically: planning and reporting
Year 5 · Chapter 1

Working scientifically: planning and reporting

By the end of this chapter you will be able to

  • Name the independent variable, the dependent variable and the control variables in a test
  • Choose an instrument with a fine enough scale, take repeat readings and find the mean
  • Record results in a table, and draw a bar chart, a line graph or a scatter graph that can be read correctly
  • Use a pattern in results to make a prediction, and plan a further test
  • Write a conclusion that matches the results, and say how much a result can be trusted
  • Say whether evidence supports or refutes an idea

You should already know

  • Fair tests, and changing only one thing at a time (Year 3 Science, Chapter 1)
  • Measuring length, and recording results in a table (Year 4 Maths and Science)

Where this leads

  • Forces, gravity and resistance, where fair tests are used again (Year 5 Science, Chapters 9 and 10)
  • Solutions and separating mixtures, with careful measurements (Year 5 Science, Chapter 6)

National Curriculum for England, Key Stage 2 science, Year 5. Content: WS1 plan different types of scientific enquiries to answer questions, including recognising and controlling variables, WS2 take measurements with increasing accuracy and precision, taking repeat readings when appropriate, WS3 record data and results of increasing complexity using diagrams, labels, classification keys, tables, scatter graphs, bar and line graphs, WS4 use test results to make predictions and to set up further comparative and fair tests, WS5 report and present findings, including conclusions, causal relationships and degree of trust in results, WS6 identify scientific evidence used to support or refute ideas or arguments.

Exercise P  Do you remember?

1
FWrite the words for a test where only one thing is changed, and everything else is kept the same.
2
FWrite the unit that would be used to measure the length of a pencil on a ruler marked in centimetres.
3
FFill in the gap: results from a test are best recorded in a ___. Write the word.
4
FWhat do you call a guess about what will happen in a test, written before the test is done? Write the word.
5
FWrite the word for the thing that you measure in a test.
1.1

Planning a fair test

Year 5
WS1: plan different types of scientific enquiries, recognising and controlling variables
Video lesson: Planning a fair testComing soon
Story. Ruby wants to know whether the height of a ramp changes how far a toy car rolls. Her teacher, Mr Patel, says: “Before you start, decide what you will change, what you will measure, and what you will keep the same.”

A scientific enquiry starts with a question, and a plan that can answer it. Scientists can plan different types of enquiry:

In a fair test there are three kinds of variable. A variable is a thing that can change.

heightdistance rolledChanged on purpose: ramp heightMeasured: distance rolledKept the same: car, surface,release point
A toy car on a ramp. The ramp height is changed, the distance rolled is measured, and the car, surface and release point are kept the same.

Key ideas

  • A fair test changes only one thing: the independent variable.
  • The dependent variable is measured. It is the result of the test.
  • Control variables are kept the same, so the test is fair.
  • Other types of enquiry include pattern seeking, classifying and research.
Worked example 1.1.1
Look at the diagram in section 1.1. Which variable is kept the same during Ruby’s test: the ramp height, or the surface? Write the words.

Method. Read the labels in the diagram.

  1. Find the label for the same things. The labels say the car, surface and release point are kept the same.
    Kept the same: car, surface
  2. Choose the one that is kept the same. The surface is kept the same. The ramp height is the thing that is changed.
    the surface
  3. Write the answer.
    the surface

Check. Only the ramp height is changed on purpose. ✓

Watch out. The changed variable is never a control variable.

Worked example 1.1.2
Mo changes the mass of a toy car and measures how long it takes to roll down a ramp. Write the dependent variable.

Method. Find the variable that is measured.

  1. Find the change on purpose. Mo changes the mass of the car on purpose, so mass is the independent variable.
    mass
  2. Find the measurement. Mo measures how long the car takes to roll, so time taken is the dependent variable.
    time taken
  3. Write the answer.
    time taken

Check. The time depends on the mass Mo chose. ✓

Worked example 1.1.3
Mo’s test is about the mass of the car. Write one control variable he should keep the same.

Method. Think about what else could change the time.

  1. Think about the test. The ramp, the surface and the release point could all change the time.
    ramp, surface, release
  2. Choose one to keep the same. Any one of these must stay the same for the test to be fair.
    Accept any one
  3. Write the answer.
    Accept any one of: the ramp height, the surface, the release point.

Check. Keep the control variables the same. ✓

Watch out

Watch out: a variable that you keep the same is a control variable. It is not the dependent variable, because you do not measure it.

Try it (with your teacher or a grown-up). Put a book under one end of a ramp (a board or a tray will do). Roll a toy car from the same starting point, three times with one book, and three times with two books. Keep the car, the surface and the starting point the same. Which variable did you change on purpose?

Exam tip

Grown-up tip. Ask: “What did you change on purpose? What did you measure? What did you keep the same?” Your child should answer with the words independent, dependent and control.

Exercise 1A  Planning a fair test

1
FRuby changes the height of a ramp and measures how far a toy car rolls. Which variable does Ruby change on purpose? Write the words.
2
FIn the same test, which variable does Ruby measure? Write the words.
3
FFill in the gap: the variable you change on purpose is the ___ variable. Write one word.
4
FFill in the gap: the variable you measure is the ___ variable. Write one word.
5
FName one control variable in Ruby’s test. Write the words.
6
PSWorking scientifically. Plan a fair test. Tom changes the car, the ramp and the surface all at once to see what happens. Is this a fair test? Write yes or no.
7
FPriya counts how many birds visit the school garden each morning for one week, and writes the numbers in a table. Is this a fair test or pattern seeking? Write the words.
8
FMo tests a ramp at 2 cm, 4 cm and 6 cm, and changes only the height each time. How many variables does Mo change on purpose? Write the number.
9
FAisha tests whether the number of paper clips on a paper plane changes how far it flies. Write the independent variable.
10
FFor the paper plane test in the question before this one, write the dependent variable.
11
PSAisha throws each plane in the same way every time. Is the throw a control variable? Write yes or no.
12
RExplain why the release point of the car must stay the same in Ruby’s test. Write one sentence.
1.2

Measuring with increasing accuracy

Year 5
WS2: take measurements with increasing accuracy and precision, taking repeat readings when appropriate
Video lesson: Measuring with increasing accuracyComing soon
Story. Priya measures the length of a bench with a ruler. Her first reading is different from her friend’s. “Let’s measure it three times, with a ruler that has millimetre marks,” says Priya.

Precision means how finely a measurement can be read. A ruler marked in millimetres is more precise than a ruler marked in centimetres, because its smallest step is smaller.

Accuracy means how close a measurement is to the true value.

To improve a measurement, use an instrument with a finer scale, and take repeat readings. Add the readings together and divide by how many there are. This is the mean. If one result is very different from the others, it is anomalous. Check it, and if there is a clear reason it was wrong, leave it out of the mean.

InstrumentSmallest step on the scale
Ruler marked in cm1 cm
Ruler marked in mm1 mm
Measuring cylinder marked every 10 ml10 ml
Measuring cylinder marked every 1 ml1 ml
3638404244464850Three trials (cm)mean 43
Three trials, 41 cm, 45 cm and 43 cm, on a number line. The mean of 43 cm is marked with a triangle.

Key ideas

  • Precision is how finely a measurement can be read.
  • Accuracy is how close a measurement is to the true value.
  • Repeat readings are added together and divided by the number of readings to find the mean.
  • An anomalous result is very different from the others, and can be left out of the mean if there is a clear reason.
Worked example 1.2.1
Priya’s three trials are 41 cm, 45 cm and 43 cm. Work out the mean. Write the number of centimetres.

Method. Add the three trials, then divide by three.

  1. Add the trials. The three trials add together to make 129 cm.
    41 + 45 + 43 = 129
  2. Divide by the number of trials. There are three trials, so divide 129 by 3.
    129 divided by 3 is 43
  3. Write the answer.
    43

Check. Check: 43 + 43 + 43 = 129. ✓

Watch out. Divide by the number of readings, which is three here.

Worked example 1.2.2
Which is more precise: a ruler marked in millimetres, or a ruler marked in centimetres? Write the unit of the smaller step.

Method. Compare the smallest steps.

  1. Read the two rulers. One ruler has steps of 1 cm, and the other has steps of 1 mm.
    1 cm and 1 mm
  2. Choose the finer scale. A smaller step means the ruler can be read more precisely.
    smaller step
  3. Write the answer.
    mm

Check. There are 10 millimetres in every centimetre. ✓

Worked example 1.2.3
Four readings are 44 cm, 46 cm, 73 cm and 45 cm. The 73 cm result is anomalous. Work out the mean of the other three. Write the number of centimetres.

Method. Take out the anomalous result, then find the mean of the rest.

  1. Leave out the anomaly. The 73 cm result is very different from the others, so it is left out. The other three are 44, 46 and 45.
    44, 46, 45
  2. Find the mean. The three add to 135 cm, and 135 divided by 3 is 45.
    135 divided by 3 is 45
  3. Write the answer.
    45

Check. Check: 45 + 45 + 45 = 135. ✓

Watch out. Divide by 3, not 4, because the anomalous result has been left out.

Watch out

Watch out: a repeat reading is not the same as a copy. Measure again each time, and then find the mean. If you leave out a result, divide by the number of results that are left.

Try it (with your teacher or a grown-up). Measure the same book three times with a ruler, and write each length down. Then find the mean. Did you get the same answer each time? Measure once more with a ruler that has a finer scale, if you have one, and compare the two.

Exam tip

Grown-up tip. Ask: “Which measurement did you trust most, and why?” Let your child add the readings and divide by the number of readings.

Exercise 1B  Measuring with increasing accuracy

1
FWhich ruler is more precise: one marked in millimetres or one marked in centimetres? Write the unit of its smallest step.
2
FLook at the table of instruments in section 1.2. Which measuring cylinder is more precise? Write its smallest step.
3
FRuby measures a pot three times: 41 cm, 45 cm and 43 cm. Work out the mean. Write the number of centimetres.
4
FThree trials gave 80 mm, 82 mm and 81 mm. Work out the mean. Write the number of millimetres.
5
FWork out the mean of 10, 12 and 14. Write the number.
6
FLook at the four readings 44 cm, 46 cm, 73 cm and 45 cm. Which result is anomalous? Write the number.
7
PSAli uses the four readings 44 cm, 46 cm, 73 cm and 45 cm. He leaves out the anomalous result. Work out the mean of the other three. Write the number of centimetres.
8
PSWorking scientifically. Check the readings before you report them. Priya’s bounce heights are 30 cm, 31 cm, 52 cm and 29 cm. Which result is anomalous? Write the number.
9
FWhich word means how close a measurement is to the true value: precise or accurate? Write the word.
10
FFill in the gap: taking repeat readings helps us to find the ___ and to check our results. Write one word.
11
RExplain why the mean of three repeat readings is usually more reliable than one single reading. Write one sentence.
1.3

Recording data and drawing graphs

Year 5
WS3: record data and results of increasing complexity using diagrams, labels, classification keys, tables, scatter graphs, bar and line graphs
Video lesson: Recording data and drawing graphsComing soon
Story. Class 5 test toy cars on five ramp heights. Mr Patel says: “Your results need a clear table, and a graph that someone else can read without asking you what it means.”

Results are recorded in a table with a heading for each column, and the units in the heading, such as cm or ml.

Choose the right kind of graph for your data:

A classification key sorts things into groups by asking questions. Each question has two answers, yes or no, and each answer leads to the next question or to a group.

Ramp height (cm)Distance rolled (cm)
223
431
640
847
1055
1263
02468101214010203040506070ramp height (cm)distance rolled (cm)
Scatter graph of distance rolled against ramp height. The points are not joined.
MaterialWater soaked up in 1 minute (ml)
Kitchen roll18
Tissue12
Newspaper9
Cardboard4
05101520water soaked up in 1 minute (ml)18 mlKitchen roll12 mlTissue9 mlNewspaper4 mlCardboard
Bar chart: Kitchen roll 18 ml, Tissue 12 ml, Newspaper 9 ml, Cardboard 4 ml.
Time (minutes)Temperature (°C)
050
544
1039
1535
2032
051015200102030405060time (minutes)temperature (°C)
Line graph of the temperature of warm water in a cup, every 5 minutes, falling from 50 to 32 degrees Celsius.

Key ideas

  • A table has a heading for each column, with units.
  • A bar chart shows separate groups. A line graph shows change over time, with the points joined.
  • A scatter graph shows two measured variables, with the points not joined.
  • Every axis of a graph needs a label, with its unit.
  • A classification key uses yes or no questions to sort things into groups.
Worked example 1.3.1
Priya records how much water four materials soak up in one minute. Which graph should she draw to compare the four materials? Write the words.

Method. Think about what kind of data this is.

  1. Look at the data. Each material is a separate group, and the amount is measured for each one.
    separate groups
  2. Choose the graph. Separate groups are shown best on a bar chart.
    bar chart
  3. Write the answer.
    bar chart

Check. A bar chart compares groups side by side. ✓

Worked example 1.3.2
Look at the scatter graph. What distance was rolled from a ramp height of 12 cm? Write the number of centimetres.

Method. Find 12 cm on the ramp height axis, then read the point above it.

  1. Find the height. Look along the horizontal axis to 12 cm.
    12 cm
  2. Read the distance. The point above 12 cm is at 63 on the distance axis.
    63 cm
  3. Write the answer.
    63

Check. The table says 63 cm for a 12 cm ramp. ✓

Worked example 1.3.3
In a classification key, an animal with feathers goes to the bird group. The first question is “Does it have feathers?” and the answer is yes. Which group does the animal go into? Write the word.

Method. Follow the key from the first question.

  1. Read the first question. The question asks: does it have feathers?
    feathers
  2. Follow the answer. The answer is yes, so the key sends the animal to the bird group.
    yes, so bird
  3. Write the answer.
    bird

Check. Each yes or no answer leads to the next step in the key. ✓

Watch out

Watch out: join the points on a line graph, but not on a scatter graph. A scatter graph shows a pattern, not a line of change over time.

Try it (with your teacher or a grown-up). Choose four socks, or four small pieces of fabric, from a drawer. Use a table to record how many are cotton, and how many are wool. Then draw a bar chart with a title and labelled axes. Check that the scale on your chart goes up in equal steps.

Exam tip

Grown-up tip. Ask: “What does each axis show? What units did you use?” Let your child choose the graph and say why.

Exercise 1C  Recording data and drawing graphs

1
FWhich type of graph shows two measured variables, with points that are not joined? Write the words.
2
FWhich type of graph is best for data in separate groups, such as four materials? Write the words.
3
FWhich kind of graph shows how a measurement changes over time, with the points joined? Write the words.
4
FLook at the scatter graph in section 1.3. What distance was rolled from a ramp height of 6 cm? Write the number of centimetres.
02468101214010203040506070ramp height (cm)distance rolled (cm)
5
FLook at the scatter graph in section 1.3. Which ramp height gave a distance of 55 cm? Write the number of centimetres.
02468101214010203040506070ramp height (cm)distance rolled (cm)
6
FLook at the bar chart in section 1.3. How much water did the kitchen roll soak up in one minute? Write the number of millilitres.
05101520water soaked up in 1 minute (ml)18 mlKitchen roll12 mlTissue9 mlNewspaper4 mlCardboard
7
PSLook at the bar chart in section 1.3. How many more millilitres did the kitchen roll soak up than the cardboard? Write the number of millilitres.
05101520water soaked up in 1 minute (ml)18 mlKitchen roll12 mlTissue9 mlNewspaper4 mlCardboard
8
FLook at the line graph in section 1.3. What was the temperature of the water at 10 minutes? Write the number of degrees Celsius.
051015200102030405060time (minutes)temperature (°C)
9
PSLook at the line graph in section 1.3. By how many degrees did the water cool from 0 minutes to 20 minutes? Write the number of degrees.
051015200102030405060time (minutes)temperature (°C)
10
FA classification key asks questions with two possible answers. Write the two answers that each question can give.
11
PSWorking scientifically. Record and present the data. Ruby records the temperature of cooling water every 5 minutes, and draws a line graph. Should she join the points? Write yes or no.
12
RExplain why every axis of a graph needs a label with its unit. Write one sentence.
1.4

Predicting and planning a further test

Year 5
WS4: use test results to make predictions and to set up further comparative and fair tests
Video lesson: Predicting and planning a further testComing soon
Story. Tom has a graph that shows his car rolling further from a higher ramp. “I think a ramp of 7 cm would make it roll about the same as the ones on either side,” he says. Mr Patel replies: “Then use your pattern to predict, and test it.”

A prediction is a sensible guess based on the evidence you already have. Look for the pattern in the results. A prediction for a value between two measured values is usually more reliable than one far outside the values tested.

Once you have results, you can plan a further test. A further comparative test changes one thing in a new way, such as the surface. The results of one test help you decide what to test next.

02468101214010203040506070ramp height (cm)distance rolled (cm)7 cm: ?
Scatter graph with a dashed line at 7 cm, between the points for 6 cm and 8 cm. The distance at 7 cm is to be predicted.

Key ideas

  • A prediction is based on the evidence from earlier tests.
  • A prediction between two measured values is usually more reliable than one far outside them.
  • A test is needed to check a prediction.
  • A further test changes only one thing, so that its result is fair.
Worked example 1.4.1
Look at the scatter graph. How much further did the car roll from a 10 cm ramp than from an 8 cm ramp? Write the number of centimetres.

Method. Read the two distances from the graph.

  1. Read the distances. The car rolled 55 cm from 10 cm, and 47 cm from 8 cm.
    55 and 47
  2. Subtract. The difference is 55 minus 47, which is 8.
    55 - 47 = 8
  3. Write the answer.
    8

Check. Check: 47 + 8 = 55. ✓

Watch out. Subtract the smaller distance from the larger one.

Worked example 1.4.2
Priya’s next test changes only the surface. She tests a smooth tray and then a towel. Write the dependent variable.

Method. Find the thing that is measured.

  1. Find the change. Priya changes the surface on purpose.
    surface
  2. Find the measurement. She measures how far the car rolls on each surface.
    distance rolled
  3. Write the answer.
    distance rolled

Check. The distance depends on the surface Priya chooses. ✓

Worked example 1.4.3
Ruby predicts that a 12 cm ramp will make the car roll further than a 10 cm ramp. Her results show 63 cm and 55 cm. Was her prediction correct? Write yes or no.

Method. Compare the prediction with the results.

  1. Read the two results. The 12 cm ramp gave 63 cm, and the 10 cm ramp gave 55 cm.
    63 and 55
  2. Compare them. Ruby predicted the 12 cm ramp would go further, and 63 is more than 55.
    further
  3. Write the answer.
    yes

Check. The result matches the prediction. ✓

Watch out

Watch out: a prediction is not a fact. Test it, and change the prediction if the evidence does not agree.

Try it (with your teacher or a grown-up). Roll a toy car down a ramp made from one book, and measure how far it rolls. Then predict how far it will roll from a ramp of two books. Test your prediction three times, and find the mean. Was your prediction close?

Exam tip

Grown-up tip. Ask: “What did you predict? What pattern made you think that?” Let your child compare the prediction with the mean of the results.

Exercise 1D  Predicting and planning a further test

1
FThe scatter graph shows 40 cm for a 6 cm ramp and 47 cm for an 8 cm ramp. Is the distance for a 7 cm ramp between 40 cm and 47 cm? Write yes or no.
02468101214010203040506070ramp height (cm)distance rolled (cm)7 cm: ?
2
FFill in the gap: a prediction should be based on the ___ from earlier tests. Write one word.
3
FPriya predicts that a car will roll 75 cm from a 14 cm ramp. Is the ramp height of 14 cm inside or outside the heights tested, which were 2 cm to 12 cm? Write inside or outside.
4
RIs a prediction for a value inside the range that has been tested usually more reliable than one outside it? Write yes or no.
5
FMo wants to test whether the mass of the car changes the distance it rolls. Which variable should he change on purpose? Write the words.
6
FAisha thinks a towel will make the car roll a shorter distance than a wooden floor. Which surface should she expect to make the car roll less far? Write the word.
7
PSAli changes the ramp height and the colour of the car in one test. Is this a fair test? Write yes or no.
8
PSTom predicts that the car will roll further on a smooth tray than on the carpet. Write one reason for his prediction.
9
PSMo says: “I predicted 45 cm, and I measured 46 cm.” Is his prediction close to his measurement? Write yes or no.
10
PSWorking scientifically. Predict what will happen. Write a prediction you could test with a ramp and a toy car. Use the words height and distance in your prediction.
11
RAli says: “The car will roll 100 cm from a 14 cm ramp, so my prediction is safe.” Is his prediction safe? Write no, and give one reason in one sentence.
12
RExplain why a prediction should be tested, rather than just believed. Write one sentence.
1.5

Reporting findings, evidence and trust

Year 5
WS5: report and present findings, including conclusions, causal relationships and degree of trust in results, WS6: identify scientific evidence used to support or refute ideas or arguments
Video lesson: Reporting findings, evidence and trustComing soon
Story. Priya’s group writes a report that says: “Higher ramps make cars roll further.” Mr Patel asks: “Can you show me the evidence? How sure can we be?”

A report says what you did, what you found and what you conclude. The conclusion must match the results, and it should say no more than the evidence shows.

A causal relationship means that one thing causes a change in another. To show a cause, the test must be fair, so that only one thing changed. A pattern in results alone does not prove a cause.

The degree of trust in a result depends on how it was obtained. Results are more trusted when the test was fair, the measurements were precise, and the readings were repeated and agree.

Evidence can support an idea, when it agrees with it, or refute it, when it does not.

IdeaFairtestCollectevidenceSupport orrefute the idea
Four boxes in a row: idea, fair test, collect evidence, support or refute the idea.

The steps of a scientific enquiry go round in a loop: an idea leads to a test, the test gives evidence, and the evidence supports or refutes the idea.

Key ideas

  • A conclusion must match the results.
  • A causal relationship is when one thing causes a change in another, shown by a fair test.
  • Repeat readings, precise measurements and a fair test all increase the degree of trust.
  • Evidence supports an idea when it agrees with the idea, and refutes it when it does not.
Worked example 1.5.1
Look at the scatter graph in section 1.4. Does the graph support the conclusion that a higher ramp makes the car roll further? Write yes or no.
02468101214010203040506070ramp height (cm)distance rolled (cm)

Method. Check the direction of the pattern.

  1. Look at the points. The distance rises as the ramp height rises, for every height tested.
    rises
  2. Decide. So the evidence supports the conclusion.
    supports
  3. Write the answer.
    yes

Check. The evidence agrees with the conclusion. ✓

Worked example 1.5.2
Priya repeats her test three times, and gets similar results each time. Does repeating the test increase the degree of trust? Write yes or no.

Method. Think about repeat readings.

  1. Think about the repeats. Repeating a test shows whether the results agree.
    agree
  2. Decide. Results that agree are more trusted, so the answer is yes.
    yes
  3. Write the answer.
    yes

Check. Repeating the test helps show the result is reliable. ✓

Worked example 1.5.3
Mo’s results show no change at all in the distance when the ramp is made higher. Does this evidence support or refute the idea that a higher ramp makes the car roll further? Write the word.

Method. Compare the evidence with the idea.

  1. Read the results. The results show no change in the distance.
    no change
  2. Compare. The evidence does not agree with the idea, so it refutes it.
    does not agree
  3. Write the answer.
    refute

Check. Evidence that does not agree with an idea refutes it. ✓

Watch out

Watch out: a pattern in results does not prove a cause unless the test was fair. If two things changed at once, you cannot tell which one caused the result.

Try it (with your teacher or a grown-up). Repeat the book-ramp test from section 1.1 three times. Write a short report with three parts: what you did, what you found, and your conclusion. Say whether your conclusion matches your results, and give one reason why you can trust them.

Exam tip

Grown-up tip. Ask: “Does your conclusion match your results? How do you know the test was fair?” Let your child read the report aloud.

Exercise 1E  Reporting findings, evidence and trust

1
FWhat is the name of the part of a report that says what the results show? Write one word.
2
FMust a conclusion match the results? Write yes or no.
3
FWhich increases the degree of trust in a result: repeating the test, or doing it once? Write the word.
4
FFill in the gap: a causal relationship means one thing ___ another. Write the word.
5
FAli changes two things at once, and the car rolls further. Does this test show clearly what caused the change? Write yes or no.
6
FMo’s evidence agrees with his idea. Does the evidence support or refute the idea? Write the word.
7
FPriya’s evidence does not agree with her idea. Does the evidence support or refute the idea? Write the word.
8
FLook at the flow diagram in section 1.5. Which box comes directly after the box that says Fair test? Write the words.
9
PSWorking scientifically. Evaluate the evidence for a claim. Aisha says: “The car rolls further because it is blue.” Is this conclusion supported by a fair test? Write yes or no.
10
PSWrite one way to increase the degree of trust in a set of results.
11
PSRuby’s three results are 41 cm, 45 cm and 43 cm. They agree closely. Does this make her results more trusted? Write yes or no.
12
RExplain why two results that agree are more trusted than one single result. Write one sentence.

Chapter summary

SkillMethod
Fair testsChange only the independent variable. Measure the dependent variable. Keep the control variables the same.
MeasuringUse an instrument with a fine scale. Take repeat readings, leave out any clear anomaly, and find the mean.
Recording and graphsUse tables with units. Bar charts compare groups, line graphs show change over time, and scatter graphs show patterns.
PredictingPredict from the pattern in the evidence, and test the prediction with a further fair test.
ReportingWrite a conclusion that matches the results, and say how much the results can be trusted.
EvidenceEvidence supports an idea when it agrees with it, and refutes the idea when it does not.

Can you…?

  • I can name the independent, dependent and control variables in a test
  • I can choose an instrument with a fine scale, and find the mean of repeat readings
  • I can record results in a table and choose a bar chart, line graph or scatter graph
  • I can read values from a graph, and use the pattern to make a prediction
  • I can plan a further test, changing one thing only
  • I can write a conclusion that matches the results, and say whether evidence supports or refutes an idea

Key terms

independent variable
the variable you change on purpose in a test
dependent variable
the variable you measure; it depends on the change you make
control variable
a variable that is kept the same, so that the test is fair
fair test
a test in which only one thing is changed
precision
how finely a measurement can be read on a scale
accuracy
how close a measurement is to the true value
mean
the total of several results, divided by how many results there are
anomalous result
a result that is very different from the others
prediction
a sensible guess about what will happen, based on the evidence
conclusion
what the results show, written so that it matches the evidence
causal relationship
when one thing causes a change in another
refute
to show that evidence goes against an idea

Exercise 1Z  Check-up

1
Look at the diagram of the toy car on a ramp. Which variable is changed on purpose? Write the words.
heightdistance rolledChanged on purpose: ramp heightMeasured: distance rolledKept the same: car, surface,release point
2
Look at the diagram of the toy car on a ramp. Which variable is measured? Write the words.
heightdistance rolledChanged on purpose: ramp heightMeasured: distance rolledKept the same: car, surface,release point
3
Ruby measures a length three times: 12 cm, 14 cm and 13 cm. Work out the mean. Write the number of centimetres.
4
Which type of graph shows two measured variables, with the points not joined? Write the words.
5
Look at the scatter graph. What distance was rolled from a ramp of 10 cm? Write the number of centimetres.
02468101214010203040506070ramp height (cm)distance rolled (cm)
6
Look at the number line of three trials. What is the mean of the three trials? Write the number of centimetres.
3638404244464850Three trials (cm)mean 43
7
Is the mean of 20, 25 and 30 equal to 25? Write yes or no.
8
Look at the flow diagram. Which box comes first, before the fair test? Write the word.
IdeaFairtestCollectevidenceSupport orrefute the idea
9
Look at the line graph. What was the temperature of the water at 15 minutes? Write the number of degrees Celsius.
051015200102030405060time (minutes)temperature (°C)
10
Mo says: “The car rolls further on a higher ramp.” His test changed only the ramp height, and the test was repeated. Is his conclusion supported by his evidence? Write yes or no, and give one reason in one sentence.

Total 19 marks. Allow about 19 minutes.

Exercise 1X  Practice test questions

1
FWrite the word for a variable that is kept the same in a fair test.[1 mark]
2
FRuby changes the height of a ramp on purpose and measures the distance a car rolls. Is the distance rolled the independent or the dependent variable? Write the word.[1 mark]
3
FA thermometer is marked in steps of 1 degree. Another is marked in steps of 5 degrees. Which thermometer is more precise? Write the step.[1 mark]
4
FThree trials gave 60 cm, 64 cm and 62 cm. Work out the mean. Write the number of centimetres.[2 marks]
5
FFour results are 9 cm, 10 cm, 25 cm and 11 cm. The 25 cm result is anomalous and is left out. Work out the mean of the other three. Write the number of centimetres.[2 marks]
6
FLook at the bar chart. Which material soaked up the least water in one minute? Write the name of the material.
05101520water soaked up in 1 minute (ml)18 mlKitchen roll12 mlTissue9 mlNewspaper4 mlCardboard
[2 marks]
7
FLook at the scatter graph. Write a range that the distance for a 9 cm ramp should lie within, using the points on either side of 9 cm.
02468101214010203040506070ramp height (cm)distance rolled (cm)
[2 marks]
8
FA student changes the mass of a toy car, and measures how long it takes to roll down a ramp. Write the dependent variable.[2 marks]
9
RPriya’s test found that a rough surface makes a car roll a shorter distance than a smooth surface. Write a conclusion for her report, and give one reason why her results can be trusted.[3 marks]
10
RRuby says: “The bigger the mass of a car, the further it rolls.” In her test she changed the mass of the car and the ramp height at the same time. Is her test fair? Write yes or no, and give one reason.[3 marks]
Chapter 2: Life cycles of animals →

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