Author note — to cover (Higher)

Higher only. Build a cumulative frequency table of running totals from a grouped frequency table and plot the curve: points at upper class boundaries, joined by a smooth curve or straight segments, starting from zero at the lowest boundary. Construction only; reading medians and quartiles off the curve is the sibling page. (S3)

• Fluency — direct questions on cumulative frequency graphs, 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).