Task# Rectangle Perimeter 2

Illustrative MathematicsVaries

This task is a natural follow up for task Rectangle Perimeter 1. After thinking about and using one specific expression for the perimeter of a rectangle, they now extend their thinking to equivalent expressions for the same quantity. The open-ended last question is intended to generate a classroom discussion led by the teacher. It is important for students to understand that correct reasoning can lead to expressions that appear to be different and that the properties of operations work for letters standing for numbers, just as they worked for numbers in earlier grades, and provide a way of showing that the apparently different expressions actually represent the same value.