3P.12—Unit 3 planning an experiment

A complete experiment plan names the apparatus and method, independent/dependent/controlled variables, fair-test control, repeats, safety and the analysis that will turn measurements into evidence.

State how the outcome is measured, what could cause systematic error, how random variation will be reduced, and what biological mechanism or implication the result would test.

For plant-fibre tensile strength, keep fibre length and loading method constant, add weights consistently, repeat across fibres, record the breaking load and discuss cross-sectional area before comparing materials.

“Repeat it” is not a complete improvement. Match each limitation to a change—calibration, control, randomisation, larger sample or safer method—and say which uncertainty it reduces.