Fix the Fair Test: Force and Motion Investigation Challenge
Design a simple fair test to see how force changes the motion of an object.
Read the passages and examples below to learn about designing a simple fair test to see how force changes the motion of an object. Notice what makes an investigation fair, how to keep one variable changed at a time, and how to use repeated trials and data to support a claim.
| Toy car on a ramp | |
|---|---|
| What we change (1 variable) | the ramp height |
| What we keep the same | same car, same surface, same start |
| What we measure (the data) | how far the car rolls, in cm |
| How many trials | 3 trials, then compare the results |
Use these four lines to check any plan. If a line is missing or has more than one change, the test is not fair.
| Trial 1 | Trial 2 | Trial 3 | |
|---|---|---|---|
| Ramp height 10 cm | 42 cm | 39 cm | 44 cm |
| Ramp height 20 cm | 78 cm | 81 cm | 76 cm |
Only the ramp height changed. Trials of the same setup are close but not identical, so one trial alone is not enough.
Sort each idea by whether it keeps one variable changed at a time.
Practice questions
- 1
A student tests whether a paper airplane flies farther when the wings are folded differently. The student changes the wing fold but also changes the paper type and throws one airplane harder than the other. The student says, 'This is a fair test because I changed several things.' What is wrong with the student's claim, and how should the test be changed to make it fair?
- 2
A student says, 'I changed the ramp height and also switched to a different toy car, so I learned which change affected the motion.' What is wrong with this plan, and how should it be fixed?
- 3
A student tests a balloon rocket by measuring how far it travels after each launch. The student writes, “Launch 1: measure the distance. Launch 2: measure the distance. Launch 3: measure the distance.” A classmate says, “This is not a fair test because the student should change the launch distance each time.” Explain why the classmate is wrong and describe what repeated trials show in this investigation.
Part of the question set is shown. Generate the whole intervention, freshly themed and with an answer key, for your own class in the product.