Mauricio and Emily distinguish between area and perimeter in the context of a rectangular pizza, as the amount of pizza one gets to eat versus the distance around the pizza.
Episode Supports
Students’ Conceptual Challenges
Emily and Mauricio are asked to determine if swapping two pieces of pizza is a fair trade. Each piece is a rectangle, but the two rectangles have different dimensions. Mauricio initially focuses on the perimeter, equating it with the crust of the pizza slice, while Emily emphasizes the importance of considering the area, representing the edible part of the pizza. The difference between perimeter (a one-dimensional measurement) and area (a two-dimensional measurement) can be challenging for students. While it isn’t clear if Mauricio thinks area is the perimeter, over the course of this lesson he does build productive ideas about area and how to measure it.
Focus Questions
For use in a classroom, pause the video and ask this question:
[Pause the video at 0:24] Before you continue, pause and consider: How would you determine if trading pizza slices between Luna and Dylan is fair? What mathematical ideas or tools can you use?
Supporting Dialogue
[Pause the video at 2:46] Emily has mentioned the word area, and when asked what that means, Mauricio traces his finger around the outside of the pizza and talks about the crust. Talk with a partner about this: What do you think area means? Is Mauricio correct when he talks about the crust? If not, what mathematical idea is Mauricio talking about?
