Author note — to cover

Identify outliers informally as values far from the pattern, in lists and on scatter graphs; decide whether to exclude one as an error or keep it as genuine, and state its effect on the mean, median, mode and range. No quartile-based rule: the 1.5 times IQR test is A level. Both tiers. (S4)

• Fluency — direct questions on outliers, 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).