Three sessions on where the interest rate in every other unit comes from — and the one that will probably teach you something too.

Corbin Falls Savings takes a $10,000 deposit and lends $9,000 of it. Follow that through four rounds and the same $10,000 is supporting $34,390 of deposits. Nothing was stolen. That is what a fractional reserve system is, and seeing it as a table rather than a slogan is the point.

Then the bank run — which turns out to be arithmetic rather than panic — and what a two-point rate change does to a car loan and to the town's own bridge.

Every figure is verified arithmetic. The unit never cites a current rate, so it does not go stale.

WHAT'S INCLUDED

Written by a licensed K-12 business teacher with more than thirteen years in the classroom. Built to be taught by a parent with no background in the subject.