Fair Testing: Try It, Fix It

Science · Scientific Inquiry · ages 8-11

Name ______________________ Date ____________

A fair test only works if you keep everything the same except the one variable you're testing.
Circle one: True False
In a fair test, what should you change between trials?
- Only the one thing you are testing
- As many things as you can
- Whatever you feel like changing
What do we call the moment a prototype breaks, jams, or stops working during a test?
- A fair test
- A failure point
- A variable
During a bridge test, the middle of the bridge sags and touches the table when weight is added. What does this tell you?
- The middle of the bridge is a weak point
- The test was not fair
- The bridge needs a new color
Zac wants to know which paper airplane flies farther: big wings or small wings. He throws the big-wing plane hard and the small-wing plane softly. Is this a fair test?
- Yes, because he tested both planes
- Yes, because he measured how far each one flew
- No, because the throwing force changed too
If your prototype fails in one spot during testing, you should throw out the whole design and start something totally different.
Circle one: True False
Leo tests two ramps to see which makes a toy car go faster. Ramp A is steeper and smoother. Ramp B is less steep and rougher. The car goes faster on Ramp A. Can Leo be sure steepness caused the speed difference?
- Yes, because he used the same toy car both times
- Yes, because Ramp A won the test
- No, because the surface also changed, so it's not a fair test
Priya's model umbrella flips inside out at the edges in wind. She plans to test it in stronger wind next, without changing the umbrella. Is this a good next step?
- Yes, stronger wind will fix the flipping
- No, she should fix the weak edges first, then retest
- Yes, as long as she uses a different color umbrella

Answer key

For grown-ups. Fold this page away before handing over the rest.

Fair Testing: Try It, Fix It W1-mt_eoPcc4nrBE-s1

True · If you change more than one thing, you won't know which change caused the result.
Only the one thing you are testing · Changing just one thing means any difference in the result must be because of that one thing.
A failure point · Failure points show you exactly where a design needs to be stronger or different.
The middle of the bridge is a weak point · When part of a design sags or touches something it shouldn't, that spot is a weak point worth fixing.
No, because the throwing force changed too · Zac changed two things, the wings and the throwing force. He can't tell which one changed the flight.
False · One weak spot doesn't mean the whole idea is bad. Fix that spot and test again.
No, because the surface also changed, so it's not a fair test · Because the surface changed too, Leo can't tell if steepness or smoothness made Ramp A faster.
No, she should fix the weak edges first, then retest · Testing in stronger wind without fixing the flipping edges just repeats the same failure, only worse.