Author note — to cover (Higher)

Higher only. Why root a times root a returns a, and (k root a) squared = k squared a; instant evaluation without expanding digits. This is the rule rationalising and expanding depend on, so drill it alone; two-term squares like (1 + root 2) squared live on expanding-surds. (N8)

• Fluency — direct questions on squaring a surd, 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).