A 3rd-grade teacher, committed to helping her students connect their mathematics problem-solving skills to the real-world, brings in grocery ads from the newspaper. Today the ads are for brownie mixes from two companies: Martha White's 10-oz for $0.99 and Pillsbury's 15-oz for 2/$3. She asks the students: "Which is a better deal?" An 8-year-old boy responds with great certaintyas though this were an easy task"Martha White. Because it's 2 for 2 dollars. This other one is 2 for 3 dollars."

A 5th-grade teacher in the same school borrowed the ads. She also asks her students: "Which is a better deal?" An 11-year-old boy responds with less confidence, "They're the same. Thirty ounces would be 3 dollars for the Martha White, and 30 ounces would be 3 dollars for the Pillsbury. Am I right?"