Author note — to cover

Express routes between labelled points of triangles, parallelograms and grids in terms of a and b, a vector travelled backwards picking up a minus sign, choosing paths through known vertices. Diagrammatic representation and addition keep this at both tiers under G25; midpoints, ratios and formal proofs are Higher siblings. (G25)

• Fluency — direct questions on routes around a figure, 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).