Explain money's three functions and how banks create money through lending.
Strip away the paper and money is a technology with three jobs: a medium of exchange (beats hauling chickens to the dentist), a unit of account (one yardstick for comparing everything), and a store of value (moves purchasing power into the future). Anything doing all three IS money — gold, paper, database entries. Modern dollars are fiat money: valuable not because they're backed by metal, but because everyone accepts them and taxes must be paid in them. Money is a shared agreement.
Banks aren't vaults; they're matchmakers between savers and borrowers — and in the matching, they create money. Deposit $1,000; the bank keeps a fraction as reserves and lends, say, $900. You still hold $1,000 in your account; the borrower holds $900 of spendable funds. The money supply grew. That's not a scandal — it's how banking works, why interest exists (rent on money), and why a panic where everyone withdraws at once can break even an honest bank.
Mastery looks like: They can name the three functions, run a reserve-and-lend calculation, and explain a bank run's logic.
Common stumbles: Believing banks keep everyone's cash in a vault; thinking "creating money" means printing paper.