Controls and Fair Tests Worksheet

Question 1

To test whether a coating affects how much dye a sample absorbs, which condition should be the same in both trials?

1. The presence of the coating
2. The amount of dye exposure
3. The measured dye uptake
4. The outcome of the test

Question 2

One coated sample soaks twice as long as an uncoated sample. Explain why the difference in dye uptake cannot be attributed to the coating alone.

Write your answer and work on the printable worksheet, or answer online.

Question 3

Which measurement directly records dye uptake in the model?

1. Time before the experiment starts
2. The amount of dye retained by the sample
3. The cost of the coating
4. The color of the empty beaker

Question 4

Explain how a repeated trial helps check a controlled comparison.

Write your answer and work on the printable worksheet, or answer online.

Question 5

Which pair isolates the effect of the coating on dye uptake?

1. P and Q
2. P and R
3. Q and R
4. All pairs

Question 6

By how many milligrams does the coating reduce uptake in the matched 10-minute trials?

Write your answer and work on the printable worksheet, or answer online.

Question 7

Which pair can test the effect of soaking time when a coating is present?

1. P and Q
2. P and R
3. Q and R
4. No pair

Question 8

Propose one new trial to test the coating at 20 minutes. State the trial to use for comparison.

Write your answer and work on the printable worksheet, or answer online.