실제 입력
- Topic and source
- Opportunity cost: value of the next best alternative forgone when a choice is made; may be non-monetary. Objective: distinguish it from sunk cost and apply it to short scenarios. Source example: cheaper train may cost more when two hours of lost paid work are included. Sunk cost: already incurred and unrecoverable, should not affect current marginal choice.
- Learner state
- First-year student says: 'Opportunity cost is all the money you lose when choosing something.' Confidence 7/10. Often counts every rejected option. No accessibility needs stated.
- Dialogue rules
- Up to 6 questions, medium difficulty. Ask one at a time. Hint ladder: ask for a concrete alternative, then restate 'next best,' then provide the train example only if needed. Correct after two unsuccessful probes or an explicit request. Stop early if the learner correctly defines, distinguishes, gives a counterexample, and transfers.







