In this problem, we engage our students in a consideration of how others might have approached the Pizza Crusts problem, probing them to identify the misconceptions about perimeter and area.

Since our lesson is based on student misconceptions, we chose two responses from previous student work and pushed students to deepen their thinking about area.

We chose the first problem because it was a square, and had students find the area of it. Patty and I found that it was common that students confused area and perimeter, even at the 7th grade level. They kept thinking of area less as a concept and more of a process: "Is that the one where I add? Or the one where I multiply?" So in our first problem, we gave them a square and gave them two possible answers, asking which was right and why. Focusing on "why" helped bring this problem alive--pushing their thinking to a different level for this group of students.

Since our lesson is based on student misconceptions, we chose two responses from previous student work and pushed students to deepen their thinking about area.

We chose the first problem because it was a square, and had students find the area of it. Patty and I found that it was common that students confused area and perimeter, even at the 7th grade level. They kept thinking of area less as a concept and more of a process: "Is that the one where I add? Or the one where I multiply?" So in our first problem, we gave them a square and gave them two possible answers, asking which was right and why. Focusing on "why" helped bring this problem alive--pushing their thinking to a different level for this group of students.