L021 · Allow 10–15 minutes for learners ready to move on. Answers are available after an attempt.
Rearrange A=πr² for positive r, then find r when A=49π cm².
r=√(A/π), so r=7 cm.
Rearrange v=u+at for t and identify when the rearrangement is invalid.
t=(v−u)/a, provided a≠0.
Lesson L021: Formulae and rearranging
Objective: Substitute into formulae and change the subject by inverse operations. State necessary restrictions and check with values.
60-minute structure: 0-7 Connect & Check; 7-14 Share; 14-25 Present/model; 25-44 Apply route choice/practice; 44-52 independent exam-style check; 52-60 Recall & Review, WWW/EBI and next step.
I represented the algebraic structure accurately, kept each transformation valid and checked the result by substitution, graph or equivalent reasoning.
I will show the missing inverse operation or algebraic step, keep signs and brackets accurate and test the result in the original relationship.
Stretch: Rearrange A=πr² for positive r, then find r when A=49π cm².
Deep challenge: Rearrange v=u+at for t and identify when the rearrangement is invalid.