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K-5 Grade 3 Unit 7 Lesson 8

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•K-5 Math 6-8 Math 9-12 Math

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Kindergarten Grade 1 Grade 2 •Grade 3 Grade 4 Grade 5

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Lesson 8

Warm-up Activity 1 Activity 2

Unit 7, Lesson 8

Find the Perimeter

Grade 3

Warm-up

Number Talk: Decreasing Dividend

Find the value of each expression mentally.

Activity 1

Ways to Find Perimeter

What do you notice? What do you wonder?

Diagram. 2 rectangles. One on a 5 by 3 dot grid, one with sides marked 5 and 3.

Find the perimeter of each shape. Explain or show your reasoning.

Activity 2

Something Is Missing

Find the perimeter of this rectangle. Explain or show your reasoning.
All the short sides of this figure are the same length, and all the angles are right angles. Find the perimeter of the figure. Explain or show your reasoning.
This octagon has all equal side lengths. Find the perimeter of the octagon. Explain or show your reasoning.

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