3.P2—Controlling variables

Identify and state how to control variables to improve experimental validity.

Use .p2—controlling variables to connect the rule to the data and decision in the question.

This matters because .p2—controlling variables determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply .p2—controlling variables to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: .P2—Controlling variables is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.