Author note — to cover

Cover finding how many periods growth or decay needs to pass a target: multiply period by period or trial powers, answer as a whole number of periods, and justify by showing the balances either side of the target. Include decay dropping below a threshold. Logarithms are A level and must not appear. Both tiers. (R16)

• Fluency — direct questions on finding how long growth takes, limited to this lesson's stated scope (4 questions).
• Application — use the same skill in unfamiliar or contextual questions without introducing a later method (4 questions).
• Check — questions built around the exclusions and likely misconceptions named in the lesson brief (4 questions).