The Economy Around You — Opportunity cost in the choices you make all day.
Every choice has an opportunity cost: the value of the next best thing you give up, even when no money changes hands.
Spending an evening one way means not spending it another. Even free time and free things carry a cost in forgone alternatives.
Sunk cost: Money already spent that cannot be recovered. Good decisions ignore it and focus only on future costs and benefits.
Asking 'what else could I do with this money or time' surfaces the opportunity cost and turns an automatic choice into a deliberate one.
12 practice questions with explanations. Free, and no account is needed to start.