Year 5 Science: Predicting and planning a further test
Part of the Year 5 Science working scientifically: planning and reporting chapter. Chapter overview · whole chapter on one page
Predicting and planning a further test
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.
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.
Method. Read the two distances from the graph.
- Read the distances. The car rolled 55 cm from 10 cm, and 47 cm from 8 cm.55 and 47
- Subtract. The difference is 55 minus 47, which is 8.55 - 47 = 8
- Write the answer. 8
Check. Check: 47 + 8 = 55. ✓
Watch out. Subtract the smaller distance from the larger one.
Method. Find the thing that is measured.
- Find the change. Priya changes the surface on purpose.surface
- Find the measurement. She measures how far the car rolls on each surface.distance rolled
- Write the answer. distance rolled
Check. The distance depends on the surface Priya chooses. ✓
Method. Compare the prediction with the results.
- Read the two results. The 12 cm ramp gave 63 cm, and the 10 cm ramp gave 55 cm.63 and 55
- Compare them. Ruby predicted the 12 cm ramp would go further, and 63 is more than 55.further
- 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
Method. Think about where 7 cm sits between 6 cm and 8 cm.
- Find the position. 7 cm lies between 6 cm and 8 cm.between 6 and 8
- Check the distances. The distances for those heights are 40 cm and 47 cm, so the answer for 7 cm lies between them.between 40 and 47
- Write the answer. yes
Check. A prediction for a value between two results should lie between their values. ✓
Method. Think about what a prediction is built from.
- Think about the basis. A prediction is a sensible guess based on what we have already measured.already measured
- Fill the gap. What we have already measured is the evidence.evidence
- Write the answer. evidence
Check. Evidence is the results and observations we already have. ✓
Method. Compare 14 cm with the heights that were tested.
- Read the range. The heights tested were from 2 cm to 12 cm.2 cm to 12 cm
- Compare. 14 cm is bigger than 12 cm, so it is outside the range.outside
- Write the answer. outside
Check. A prediction outside the range tested is less reliable. ✓
Method. Think about the evidence for each kind of prediction.
- Think about inside values. A value inside the tested range is supported by the results around it.supported
- Decide. So a prediction inside the range is usually more reliable.yes
- Write the answer. yes
Check. Outside the range there is no evidence to support the pattern. ✓
Method. Find the variable that Mo changes on purpose.
- Read the plan. Mo wants to test whether the mass of the car changes the distance.mass of the car
- Name the variable. The variable changed on purpose is the mass of the car.the mass of the car
- Write the answer. the mass of the car
Check. The mass is the only thing that changes in a fair test of mass. ✓
Method. Think about a rough surface.
- Think about the towel. A towel is rough, so it slows the car more.rough
- Make the prediction. So the car should roll less far on the towel.towel
- Write the answer. towel
Check. Aisha can test this prediction with a fair test. ✓
Method. Count the things that change.
- Count the changes. Two things change: the ramp height and the colour of the car.two things
- Decide. Only one thing should change in a fair test, so the answer is no.no
- Write the answer. no
Check. Ali should change one thing only. ✓
Method. Think about the surface.
- Think about the tray. A smooth tray is less rough than carpet.less rough
- Write the reason. Less friction means the car keeps moving for longer.less friction
- Write the answer. Accept any reason that says a smooth surface makes less friction, so the car rolls further.
Check. Test the prediction with a fair test. ✓
Method. Compare the prediction with the measurement.
- Find the difference. The difference between 46 cm and 45 cm is only 1 cm.1 cm
- Decide. A difference of 1 cm is close, so the answer is yes.yes
- Write the answer. yes
Check. Close predictions show the pattern was a good guide. ✓
Method. Use the pattern from the graph.
- Use the pattern. The graph shows that a higher ramp gives a longer distance.higher ramp
- Write the prediction. So a higher ramp should make the car roll a longer distance.longer distance
- Write the answer. Accept any prediction that says a higher ramp makes the car roll a longer distance.
Check. Test your prediction three times, and find the mean. ✓
Method. Think about the range of the evidence.
- Read the range. The heights tested were 2 cm to 12 cm.2 cm to 12 cm
- Decide. 14 cm is outside that range, so the prediction is less reliable.outside the range
- Write the answer. No. Accept any reason that says 14 cm is outside the heights tested, so the prediction is less reliable.
Check. Predictions outside the tested range need checking with a further test. ✓
Method. Think about what a test does.
- Think about the test. A test gathers new evidence about the prediction.new evidence
- Write the reason. The result shows whether the prediction matches the evidence.matches the evidence
- Write the answer. Accept any sentence that says a test shows whether the evidence matches the prediction.
Check. A prediction is a guess until it is tested. ✓