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Fair testing (age 8+)

Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved

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What a learner can do afterwards

  • Plan a fair test of a prototype with clearly identified variables to control
  • Carry out the test and identify failure points or weaknesses in the design
  • Propose specific improvements based on test results and retest

The lesson

A fair test compares two designs by changing only one thing at a time. That one thing is called the variable. Everything else, like the tools you use and how you measure, stays exactly the same. This way, you know what really caused the result you see.

Try it together

Mia built two paper boats to find out which sail shape catches more wind. She used the same fan, the same water, and the same starting spot for both boats. She only changed the height of the sail. Boat A had a short sail and moved 6 steps. Boat B had a tall sail and moved 9 steps. Because the sail was the only thing that changed, Mia knew the taller sail made the boat go farther.

Boat A6Boat B9
Good to know

While you test, watch closely for failure points, the moments when the prototype breaks, jams, or does not work the way you planned. Write these down, even if the test still finishes.

Good to know

Use what you found to make one specific change. Then run the same fair test again to see if that change actually helped.

Change one thing, watch closely for what breaks, then fix that one spot and test again.

Watch it

Where it sits

Where this leads

Jobs that lean on this skill. Follow one to see everything it is built on.

Then practise

8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.

Fair testing (age 8+) · Science, ages 8 to 11 · LightMySky