Author note — to cover

Why x squared = k has two solutions while the root sign denotes only the positive one; plus-or-minus notation; giving both roots of 49. Solving quadratic equations lives in Algebra; roots of negatives have no real value at GCSE, and complex numbers are A level. Both tiers. (N6)

• Fluency — direct questions on positive and negative square roots, 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).