Primary 3 · Science · Process Skills: Fair Test & Variables
Process Skills: Fair Test & Variables questions for Primary 3 Science
10 questions to work through online, 2 of them written out the way the paper asks. Answer and you get the working straight away, then a score at the end. No sign-up, and you can retake it as often as you like.
- Changing one thing
- Choosing set-ups to compare
- What to keep the same
- Spotting an unfair test
- Reading results
- Improving a test
- What the results do not show
- Naming the thing being changed
- Naming the thing measured
- Why repeat a test
| Ball | Height dropped from (cm) | Height bounced to (cm) |
|---|---|---|
| A | 50 | 30 |
| B | 50 | 18 |
| C | 50 | 42 |
Answers and explanations for all 10 questions
Every answer with the reasoning behind it. Worth reading after you have tried the set — or on its own, if you are a parent marking it.
In a fair test, how many things should be changed at a time?
Answer: one
Exactly one thing is changed, so that any difference in the result must have been caused by that one thing.
Which two set-ups shown above should be compared to find out if seeds need light to grow?
Answer: E and F
To test light, the two set-ups must differ in light and nothing else. E and F both get 10 ml of water and differ only in whether they are in sunlight.
Priya wants to find out whether a paper aeroplane flies further when it is thrown harder. Which two things must she keep the same?
Answer: A and B only
Everything stays the same except the one thing being tested. She is testing how hard she throws, so that is what changes; the aeroplane and the starting place must not.
Sam tested which of two cloths dries faster. He hung the first cloth outside in the sun and the second inside the house. Why is his test not fair?
Answer: The two cloths were not dried in the same conditions.
One cloth was in the sun and one indoors, so any difference could have been caused by the place rather than by the cloth. Both must be dried in the same conditions.
Based on the table above, which statement is correct?
Answer: Ball C bounced the highest of the three.
C bounced to 42 cm, higher than A at 30 cm and B at 18 cm. The other statements go beyond what was measured.
A class tested how long an ice cube takes to melt in a cup. Which changes would make their test more reliable?
Answer: A, B and D only
Same-sized cubes, the same starting moment and repeating the test all make the results more trustworthy. Using a different room each time introduces a difference in temperature that nobody is measuring.
Wei Ming found that a plant in the window grew taller than the same kind of plant in a cupboard. What can he correctly conclude?
Answer: The plant in the window grew taller than the one in the cupboard.
A conclusion may only say what the results actually show. He compared two plants and one grew taller; anything about all plants, or about the best place, goes beyond the test.
Nadia rolled the same toy car down ramps set at three different steepnesses and measured how far it travelled. What is the one thing she changed on purpose? The ______ of the ramp.
Answer: steepness
The one thing changed on purpose is the steepness of the ramp; everything else was kept the same.
In the same experiment, Nadia wrote down how far the car travelled each time. What is that called — the thing she measured? The ______ .
Answer: result
The distance she wrote down is the result — the thing measured to see what the change did.
Why does a class repeat an experiment several times instead of doing it once?
Answer: so that one odd result does not mislead them
Any single measurement can go wrong — a slip of the timer, a gust of wind. Repeating shows whether the result holds, so that one odd result does not mislead them.