Author note — to cover

Draw a line of best fit by eye: straight, following the trend, points balanced either side, not forced through the origin and never point-to-point. Include judging when no sensible line exists because correlation is too weak or non-linear. Using the line for estimates is the sibling page; least-squares regression is A level. Both tiers. (S6)

• Fluency — direct questions on the line of best fit, 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).