Author note — to cover

Checking a completed calculation by the inverse operation, across the four operations and powers against roots; choosing which inverse statement verifies a given result. Estimation-based checking lives on Measures checking-answers; regrouping for easier arithmetic lives on reordering-a-calculation. Both tiers. (N3)

• Fluency — direct questions on checking an answer with the inverse operation, 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).