Distinguish extension from total length in practical measurements.

In the subtopic Stretching and deformation, this learning objective focuses on distinguish extension from total length in practical measurements. For AQA GCSE Physics 8463 Unit 4.5 Forces, keep the explanation inside Stretching and deformation and Forces and elasticity. Approved keywords for this objective include extension. A strong answer separates scalar and vector quantities, uses correct units where quantities are involved, and links the physical reasoning back to distinguish extension from total length in practical measurements. This is not a generic revision point: it is specifically about Stretching and deformation, Forces and elasticity, and the approved wording of the learning objective.