Goal: apply a stipulated AUD→USD rate and invert it when converting back. 25 = 2 + 5 + 6 + 7 + 5.
- 0–2: Read Card M: in this invented model only, AUD1 = USD0.64 and no fees. Display “not a live quote.”
- 2–7: Model AUD250 ×0.64 = USD160. Reverse-check USD160 ÷0.64 = AUD250, preserving currency labels.
- 7–13: Learners separately convert USD96 ÷0.64 = AUD150 and reverse ×0.64 = USD96. An estimate notes AUD amount should be numerically larger here because each AUD maps to less than one USD in this model.
- 13–20: Routes: move currency cards through the direction arrows; fill the labelled two-way table; use the optional offline rate switch or write/speak both expressions and check them by hand. Every route states rate date/fees are unknown in reality; no live rate is fetched.
- 20–25: Exit “USD96 ×0.64 gives what, and why is it not the requested AUD amount?” Key: it applies the AUD→USD direction to the wrong starting currency. Move: write the source unit above each number, then choose multiplication/division.
Alternative domains: invented travel itinerary or digital licensing estimate. Optional/home: change a made-up conversion factor and predict direction; do not look up or use a live rate. Two optional swaps.