Author note — to cover (Higher)

Higher only (G10): the perpendicular from the centre bisects a chord, and radii create isosceles triangles, with Pythagoras finding half-chord lengths and distances from the centre. This is the workhorse fact for mixed circle problems and links back to Mensuration's Pythagoras pages. (G10)

• Fluency — direct questions on chords and the centre, 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).