Author note — to cover

Calculate the range as largest minus smallest, stated as a single number, and interpret it as consistency; stress it measures spread and is not an average. Show one outlier stretching it. Ranges from tables sit on the table pages; the outlier-resistant interquartile range is Higher, in the Quartiles group. Both tiers. (S4)

• Fluency — direct questions on the range, 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).