Author note — to cover (Higher)

Higher only. Find the lower and upper quartiles of small ordered lists using the quarter and three-quarter positions, with lengths like 7, 11 and 15 so positions land on actual values. Insist on ordering first. Reading quartiles off cumulative frequency curves sits on Presenting data; the interquartile range is the sibling page. (S4)

• Fluency — direct questions on quartiles from a list, 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).