Teacher copy: This page may include teaching prompts or answer keys. Answer keys in this public library can be viewed by anyone. Give learners a clean prompt, use checks as formative evidence, and change a case locally when prior access matters.
Goal: use the cost base to calculate a fictional mark-up and selling price. 25 = 2 + 5 + 6 + 7 + 5.
0–2: Show Card J's $80 stated unit cost and 25% mark-up on cost. Ask which number supplies the percentage base.
2–7: Model $80×0.25=$20 gap and $80+$20=$100 stated selling price; reverse check $100−$80=$20.
7–13: Learners estimate 25% as one quarter of $80 and explain why 25% of $100 would answer a different question.
13–20:Routes: place four equal cost-quarter strips on the base grid; annotate base/gap/price boxes; write or dictate price=cost×1.25 and reverse subtraction. All routes name omitted tax and other costs.
20–25: Exit “Is the $20 proven net profit?” Key: no; extra costs are omitted. Move: separate mathematical unit price gap from a business net-profit conclusion.
Alternative domains: fictional game-event badge or community theatre prop. Optional/home: model a made-up $40 base with 10% mark-up; no purchase. Two optional swaps.