A higher price. A better deal?

Each buyer receives a private value and each seller a private cost. Students choose their own bid or ask. Once orders close, anonymous step curves show the market those choices made. The curves describe submitted orders, not an assumption that students report their cards truthfully.

Before revealing the minimum-price comparison, ask who expects to benefit. The next view reuses the same orders. Buyers must be willing to pay the minimum; sellers must be willing to accept it. If willing supply exceeds demand, the lowest asks have priority, with acceptance time and a stable identifier breaking ties. The highlighted unsold interval counts actual willing sellers left without a trade.

This is a fixed-book experiment, not a forecast of long-run supply. There are no government purchases and no guaranteed sale. A fresh round could change orders, entry or behavior; discuss those possibilities without confusing them with the controlled comparison on screen.

Try the screen-and-phone preview with fictional classmates. Your phone submission uses the same input and settlement rules as the lesson. The presenter controls reveal each step; sample classmates are illustrative, not optimal strategies or real student records.