Author note — to cover

Teach simple random sampling: number the population list, use random numbers or a draw, equal chance for every member. Questions describe a valid method step by step and explain why haphazard selection is not random. Exclude stratified sampling entirely, removed from 9-1 GCSE and now A level. Both tiers. (S1)

• Fluency — direct questions on random sampling, 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).