Elasticity in the Cafeteria

Two pricing tests at a school cafeteria reveal price elasticity of demand. Students discover that raising the price of an elastic good (the bottled juice) cuts revenue, while raising the price of an inelastic good (the basic ham-and-cheese sandwich) lifts it. Across three rounds — juice test, sandwich test, and a final pricing plan — students compute %ΔQ / %ΔP, plot two demand curves, and learn the rule: raise the right price, not more prices.