B.3.5—Tangents and instantaneous rates

Draw and use the slope of a tangent to a curve as a measure of rate of change, including determining reaction order by the initial-rates method.

Use b.3.5—tangents and instantaneous rates to connect the rule to the data and decision in the question.

This matters because b.3.5—tangents and instantaneous rates determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.3.5—tangents and instantaneous rates to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.3.5—Tangents and instantaneous rates is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.