Design a Controlled Comparison

Separate a changed variable, a measured outcome, and controlled conditions.

All worksheets

5 questions0m 0s

Learn the skill

State the question as the effect of one change on one outcome. Change that factor, keep relevant conditions alike, and repeat measurements. A comparison group helps reveal what happens without the change.

Worked example

To compare paper types in bridge models, use the same span, paper size, and test method. Paper type is the changed factor; supported mass is the measured outcome.

Paper Rotor Plan

A class asks whether blade length affects a paper rotor's fall time. It will compare 4 cm and 6 cm blades, using the same paper type, body design, release height, and timing method. Each design will be dropped five times in the same indoor space. Students will alternate designs between drops.

1. What is the deliberately changed variable? Release height Blade length Timing method

2. What is the measured outcome? Paper color Blade length Fall time

3. Which change would weaken the comparison? Using a different release height for each design Repeating each design five times Using the same timing method

4. Why alternate designs between drops? To guarantee equal fall times To reduce confounding with changes over the testing period To avoid recording data

5. What should the class do with an unexpected but valid measurement? Delete it because it disagrees Replace it with the desired value Keep it and investigate why it differs

Review your work

0correct

Complete the questions to review each answer.

View dashboard