Change size only. Record size and fall time together for every trial. Repeat because releases and timing vary. Compare typical times and spread, not one fastest or slowest result.

Example: compare three sizes of one design; measure fall time from the same height, with the same paper and release method; repeat five times per size and record every time.

Answer

Example: compare three sizes of one design; measure fall time from the same height, with the same paper and release method; repeat five times per size and record every time.