Teaching Physics with the Physics Suite

Edward F. Redish

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Pizza Sale

Two Terrapins decide to go to Jerry's for a pizza. When they get there they find Jerry's is having a special:

SPECIAL TODAY:one 20" pizza$15
REGULAR PRICEone 10" pizza$5
one 20" pizza$18

Raphael goes: "Great! Let's get a large one."
Donatello goes: "Don't be dumb. Let's get three of the small ones for the same price. That'll give us more pizza and be cheaper."
Raphael goes: "Why would it be a special if it's more than we could get for regular price? Let's get the large."

Who's right? Which would you buy? What would the difference be if you were buying them at Ledo's (square pizzas)?

Page last modified September 30, 2002: G05