How it works
Cash stays put: coins in a jar are the same later, and grow nothing.
A bond is a loan with a promise. Maya lent the town 100 coins for a promise of five extra coins a year and the hundred back after three years.
A stock is a slice of a company. Ben bought ten slices of Lemon Co. and shared its good and quiet years.
The more a thing swings, the more it might give or take. Cash swings least, then bonds, then stocks.