Interest & Debt — what saving earns and borrowing costs, in your head

The money math most schools skip

What $500 in savings earns at 5%. What $500 on a credit card costs at 24% — this month, in dollars. How long money takes to double at 8% (about nine years, by the rule of 72), and how long a card balance you ignore takes to double at 18% (four). Simple interest against compound, side by side, so you can see the gap start small and widen.

Open Road is the part no worksheet covers: the minimum payment that is mostly interest, the ‘no interest for 12 months’ deal and what happens in month 13, and why paying off a card at 20% beats any savings account. Compound interest, credit and loans are missing from the BC, Alberta and Quebec curricula entirely; Ontario names them in Grade 8. Here they are twelve questions at a time.