Lesson 8
Find the Perimeter
Lesson Purpose
The purpose of this lesson is for students to find perimeters of shapes given all or some of the side lengths.
Lesson Narrative
In previous lessons, students learned about attributes of two-dimensional shapes. They also learned about perimeter and drew shapes with specific perimeters. In this lesson, students find perimeters of shapes given side lengths and use the attributes of shapes to find the perimeter given only some of the side lengths.
- Representation
- MLR8
Activity 1: Ways to Find Perimeter
Learning Goals
Teacher Facing
- Find the perimeter of two-dimensional shapes given all or some of the side lengths.
Student Facing
- Let’s find the perimeter of more shapes.
Required Materials
Materials to Gather
Required Preparation
Lesson Timeline
| Warm-up | 10 min |
| Activity 1 | 20 min |
| Activity 2 | 15 min |
| Lesson Synthesis | 10 min |
| Cool-down | 5 min |
Teacher Reflection Questions
How did students leverage their geometry knowledge about attributes of shapes to reason about perimeter in today’s lesson?
Suggested Centers
- Can You Draw It? (1–5), Stage 3: Grade 3 Shapes (Addressing)
- Which One? (K–5), Stage 4: Grade 3 Shapes (Addressing)
- How Are They the Same? (1–5), Stage 3: Grade 3 Shapes (Addressing)