Author note — to cover

Run the rectangle, triangle, parallelogram and trapezium formulas backwards to recover a base, height or parallel side from a stated area, substituting then solving a one- or two-step equation. Circle and sector reversals live on their own pages in the circles group. Both tiers. (G16, G17)

• Fluency — direct questions on finding a length from an area, 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).