Year 1 Science: Fair tests
Part of the Year 1 Science being a scientist chapter. Chapter overview · whole chapter on one page · Download worksheet (PDF) · Answers (PDF)
Fair tests
A test helps us find out the answer to a question. In a fair test, we change only one thing. Everything else stays the same. Then any difference in the results must come from the thing we changed.
We measure the results and write them down, so we can compare them.
Key ideas
- A fair test changes only one thing.
- Keep everything else the same.
- Measure the results and write them down.
- Test more than once to check your results.
Method. Read where each ball’s bounce reaches on the ruler, then compare.
- Read the red ball. Find the height on the ruler where it stopped.red ball: 30 cm
- Read the blue ball. Find the height on the ruler where it stopped.blue ball: 18 cm
- Compare the heights. The higher mark on the ruler is the higher bounce.30 cm is higher than 18 cm
- Write the answer. red ball bounced higher.
Check. Both balls were dropped from the same height, so the bounce shows which ball is bouncier. ✓
Watch out. Read the ruler at the bottom of each ball, not at the top.
Method. Think about which thing Ali is changing, and which things are kept the same.
- Find the thing that changes. Ali changes the ball. That is the one thing that changes.changes: the ball
- Find the things that stay the same. The height and the floor must be the same, so that they do not change the result.same: height and floor
- Write the answer. The height and the floor
Check. Drop both balls from the same height again. The result should be fair. ✓
Watch out. If the height changes too, you cannot know which thing made the difference.
Method. Check how many things are changed.
- Find the things that change. The ball changes, and the height changes too.two things: ball and height
- Count the changes. A fair test changes only one thing.two changes
- Write the answer. With two changes, we cannot tell which one made the difference.No. Two things changed: the ball and the height.
Check. Drop both balls from the same height and it becomes fair. ✓
Watch out. Change one thing only, and keep the rest the same.
Watch out
Watch out: if you change two things at once, you cannot tell which one made the difference. Only change one thing.
Try it at home (with a grown-up). With a grown-up, drop two different balls from the same height onto the same floor, in a safe space away from breakable things. Measure how high each ball bounces with a ruler. Do it twice. Which ball bounced higher? Write down your results.
Exam tip
Grown-up tip. Use two balls of different types, and drop each one from the height of your hand. Let your child read the ruler. Ask: “What did we keep the same?”
Exercise 1C Simple tests and fair tests
Method. Think about what makes a test fair.
- Read the question. We want to know what makes a test fair.fair test
- Think about the change. If we change only one thing, we can see what made the difference.only one change
- Write the answer. one
Check. Two changes would mix up the results. One change keeps it fair. ✓
Watch out. Change one thing, and keep the rest the same.
Method. Read where each ball’s bounce reaches on the ruler, then compare.
- Read the yellow ball. Find the height on the ruler where it stopped.yellow ball: 22 cm
- Read the green ball. Find the height on the ruler where it stopped.green ball: 14 cm
- Compare the heights. The higher mark on the ruler is the higher bounce.22 cm is higher than 14 cm
- Write the answer. yellow ball bounced higher.
Check. Both balls were dropped from the same height, so the bounce shows which ball is bouncier. ✓
Watch out. Read the ruler at the bottom of each ball, not at the top.
Method. Read where each ball’s bounce reaches on the ruler, then compare.
- Read the red ball. Find the height on the ruler where it stopped.red ball: 12 cm
- Read the blue ball. Find the height on the ruler where it stopped.blue ball: 26 cm
- Compare the heights. The higher mark on the ruler is the higher bounce.26 cm is higher than 12 cm
- Write the answer. blue ball bounced higher.
Check. Both balls were dropped from the same height, so the bounce shows which ball is bouncier. ✓
Watch out. Read the ruler at the bottom of each ball, not at the top.
Method. Think about why we test more than once.
- Look at the three results. They are 20 cm, 22 cm and 21 cm, which are close together.20, 22, 21
- Think about why we repeat. Testing again checks that the results are not a one-off.repeat to check
- Write the answer. To check his results.
Check. If the results are close, we can trust them more. ✓
Watch out. One test can be a mistake. Testing again helps us be sure.
Method. Think about what Mia wants to compare.
- Read the question. She wants to compare balls of different weights.heavier ball
- Choose the one thing. The thing that changes is the ball, so she uses a heavier one.change: the ball
- Write the answer. the ball
Check. Mia keeps the height and the floor the same. ✓
Watch out. Change the ball, and keep everything else the same.
Method. Think about what would change the bounce if it was different.
- Think about the height. If the height is different, the bounce will change too.height: keep the same
- Think about the floor. A different floor can change how high a ball bounces.floor: keep the same
- Write the answer. the height and the floor
Check. Drop each ball from the same height, onto the same floor. ✓
Watch out. Check the height is the same each time.
Method. Look at what is different between the two drops.
- Look at the first drop. The ball is dropped from 1 metre.1 metre
- Look at the second drop. The ball is dropped from 50 cm, which is lower.50 cm
- Write the answer. The height is the thing that changed.the height
Check. The ball and the floor stayed the same. Only the height changed. ✓
Watch out. 1 metre is 100 cm, so 50 cm is lower.
Method. Count how many things change between the two balls.
- Look at the balls. Two different balls are being tested.red ball and blue ball
- Look at the heights. One ball starts on the table and one on the floor.table and floor: different heights
- Write the answer. Changing the height as well as the ball means it is not a fair test.No. He changed the height as well as the ball.
Check. Drop both balls from the same height to make it fair. ✓
Watch out. Only the ball should change.
Method. Think about what the result would tell us if the height was different.
- Think about the result. If the height changes, the bounce might change because of the height.height changes the bounce
- Keep the height the same. Then only the ball is changed, so any difference comes from the ball.same height, one change
- Write the answer. So the height stays the same, and only the ball changes.
Check. Only one thing changes in the test, so it is fair. ✓
Watch out. Use the same height every time.
Method. Make a prediction first, then think about how to test it fairly.
- Make a prediction. A rug can take up some of the bounce, so the ball may bounce lower.prediction: higher on the hard floor
- Plan a fair test. Drop the same ball from the same height onto each surface.same ball, same height
- Measure and compare. Measure each bounce with a ruler, and compare the two results.Test it, then compare the bounces
Check. Check your prediction against the measurements. ✓
Watch out. A prediction is an idea. Only the test tells us if it is right.