# Lesson 16

Compare Perimeters of Rectangles

### Lesson Purpose

The purpose of this lesson is for students to apply multiplicative reasoning and their knowledge of fractions to solve problems about perimeters of rectangles.

### Lesson Narrative

This lesson reinforces students’ understanding of the relationship between the side lengths and the perimeter of a rectangle and their ability to reason multiplicatively in a geometric context.

• Action and Expression
• MLR8

### Learning Goals

Teacher Facing

• Solve problems involving the perimeter of rectangles using multiplicative comparison.

### Student Facing

• Let’s solve problems about rectangles of different sizes.

### Required Materials

Materials to Gather

Materials to Copy

• Centimeter Grid Paper - Standard

### Required Preparation

Activity 2:

• Each group of 2 needs a 12-inch pipe cleaner, an inch ruler, and tape.

### Lesson Timeline

 Warm-up 10 min Activity 1 10 min Activity 2 15 min Activity 3 10 min Lesson Synthesis 10 min Cool-down 5 min

### Teacher Reflection Questions

What evidence do you have that students' ideas about perimeter shifted or broadened as a result of this lesson?

### Suggested Centers

• Can You Draw It? (1–5), Stage 4: Area and Perimeter (Supporting)
• Rectangle Rumble (3–5), Stage 3: Factors 1–10 (Supporting)