Author note — to cover

Union, intersection, complement and the universal set, each matched to the region it shades on a two-set diagram, and read inside probability statements such as P(A union B). Exactly the GCSE four, both tiers. Exclude subset symbols, De Morgan laws and set-builder notation, which live on the extracurricular set theory page and at A level. (P6)

• Fluency — direct questions on set notation, 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).