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Primary 3 · Science · Science inquiry

Planning a fair test

Students learn to change one thing, keep other things the same and measure the result, and record findings in tables and simple column graphs.

Awaiting educator review. This material was drafted by our content team with AI assistance and is waiting for review by a qualified educator. Please check it suits your child before using it. Created 10 October 2026. How we review

These lessons were written around Australian Curriculum strands and matched to Singapore levels by age (Primary 1 is the first year of primary school). They are not aligned to MOE syllabuses or the PSLE, so check them against the syllabus your child is working towards.

Learning goals

Learners will

  • Plan a fair test by changing one thing, keeping other things the same and measuring the result.
  • Record results in a table.
  • Draw and read a simple column graph.

Success looks like

  • I can say what I will change, what I will keep the same and what I will measure.
  • I can spot why a test is not fair.
  • I can show my results in a table and a column graph and say what they tell me.

The big idea

Scientists use fair tests to answer questions. In a fair test, we change only one thing so we know that thing caused any difference in our results.

Planning a fair test means deciding three things:

  • What will I change? (only one thing)
  • What will I keep the same? (everything else)
  • What will I measure? (the result)

For the question 'Which ball bounces highest?', we change the type of ball. We keep the same drop height, the same floor and the same way of letting go. We measure how high each ball bounces.

If we dropped one ball from higher up, the test would not be fair, because we would not know whether the ball or the height made the difference.

We repeat each test three times. Results can vary a little, and repeating helps us trust them.

We record results in a results table with clear headings and units, like cm. Then we can draw a column graph: one column for each ball, with its height showing the bounce. The tallest column shows the highest bounce.

Worked examples

Plan a melting test

Plan a fair test for: 'Where does an ice cube melt fastest: in the sun, in the shade or in the fridge?'

  1. Change: the place.
  2. Keep the same: the size of the ice cubes, the type of plate, the starting time.
  3. Measure: how many minutes each cube takes to melt completely.

Answer: Change the place, keep the ice cube size and plate the same, and measure the melting time.

Spot the unfair test

Sam drops a tennis ball from 1 metre and a rubber ball from 50 cm onto the same floor. Is this fair?

  1. What did Sam want to change? The type of ball.
  2. What else changed? The drop height.
  3. Two things changed, so we cannot tell which one made the difference.

Answer: Not fair. Both balls must be dropped from the same height.

Table and graph

Bounce heights: tennis ball 50 cm, rubber ball 80 cm, foam ball 20 cm. Show these and compare.

  1. Make a table with two columns: 'Ball' and 'Bounce height (cm)'.
  2. Draw a column graph: ball names along the bottom, height in cm up the side going up in 10s.
  3. Draw columns to 50, 80 and 20.
  4. The rubber ball's column is tallest. It bounced 80 − 50 = 30 cm higher than the tennis ball.

Answer: The rubber ball bounced highest (80 cm), 30 cm higher than the tennis ball.

Practice check

Have a go, then check your answers. Each answer comes with an explanation.

  1. 1.In a fair test, how many things should you change?
  2. 2.You test which paper towel soaks up the most water. What should you keep the same?
  3. 3.Why do scientists repeat a test three times?
  4. 4.On a column graph of bounce heights, what does the tallest column show?
  5. 5.A test asks: 'Do plants grow taller with more water?' What should be changed?
  6. 6.Toy car results: carpet 35 cm, tiles 60 cm, grass 25 cm. Which surface had the longest roll?
  7. 7.Using the same results (carpet 35 cm, tiles 60 cm, grass 25 cm), how many centimetres further did the car roll on tiles than on carpet?
  8. 8.A test where only one thing is changed is called a f___ t___.
Answer guide for parents

  1. In a fair test, how many things should you change?

    One — Change only one thing so you know what caused the result.

  2. You test which paper towel soaks up the most water. What should you keep the same?

    The amount of water and the size of each piece — Only the type of towel changes; the water and size stay the same.

  3. Why do scientists repeat a test three times?

    To check that their results are reliable — Repeating helps us trust our results.

  4. On a column graph of bounce heights, what does the tallest column show?

    The highest bounce — The tallest column stands for the biggest number.

  5. A test asks: 'Do plants grow taller with more water?' What should be changed?

    The amount of water — Water is the one thing being tested, so it is what you change.

  6. Toy car results: carpet 35 cm, tiles 60 cm, grass 25 cm. Which surface had the longest roll?

    tiles — 60 cm is the largest number.

  7. Using the same results (carpet 35 cm, tiles 60 cm, grass 25 cm), how many centimetres further did the car roll on tiles than on carpet?

    25 — 60 − 35 = 25 cm.

  8. A test where only one thing is changed is called a f___ t___.

    fair test — This is a fair test.

Watch out for

  • Students often change several things at once to 'make it better'. Remind them that only one thing should change.
  • Some students think one try is enough. Repeating tests shows whether a result was a fluke.
  • Students may start the graph scale at a number other than zero or use uneven steps. Start at zero and go up in equal steps.

Tips for parents

  • Use the three planning questions (change, keep the same, measure) for every investigation you do at home.
  • Draw the results table before starting so your child knows what to record.
  • Safety: drop balls in a clear space away from windows, and keep the floor clear so no one trips.

Go further

  • Investigate whether drop height changes how high one ball bounces, using drops of 50 cm, 1 m and 1.5 m.
  • Test which paper aeroplane design flies furthest, keeping the paper size and throwing force the same.
  • Turn your results into a column graph on grid paper, using a ruler for straight columns.

About 45 minutes

Make a lesson planAssign to my child

You'll need

  • Three different balls (for example a tennis ball, a bouncy rubber ball and a foam ball)
  • A tape measure or metre ruler
  • Sticky tape to fix the tape measure to a wall
  • Paper, a pencil and a ruler for the table and graph
  • A helper to watch the bounce

Key words

fair test
A test where only one thing is changed and everything else is kept the same.
variable
Anything in a test that can change or be changed.
prediction
What you think will happen, and why, before you test.
measure
To find the size, amount, time or distance using a tool such as a ruler or timer.
results table
A table with headings that shows what you found.
column graph
A graph that uses columns of different heights to compare amounts.
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