Lesson 7 Same Perimeter, Different Shapes

- Let’s learn about shapes with the same perimeter.

Warm-up True or False: Sums of Four Numbers

Decide whether each statement is true or false. Be prepared to explain your reasoning.

$123 + 75 + 123 + 75 = 100 + 100 + 70 + 70 + 5 + 5 + 3 + 3$
$123 + 75 + 123 + 75 = (2 \times 123) + (2 \times 75)$
$123 + 75 + 123 + 75 = 208 + 208$
$123 + 75 + 123 + 75 = 246 + 150$

Activity 1 All Kinds of Shapes

10 shapes labeled A to J, on dot grid.

Choose any 3 shapes and find the perimeter of each shape. Explain or show your reasoning.
Find one shape that has the same perimeter as one of the shapes you chose earlier. Be prepared to explain your reasoning.

Activity 2 Draw Your Own

Problem 1

Draw 2 shapes with each perimeter.

12 units
26 units
48 units

Problem 2

With your partner, choose a length. Then, draw your own shape with that perimeter.
Share the shapes you drew and discuss how they are alike and how they are different.

Practice Problem

Problem 1

Draw 2 different shapes with perimeter 20 units.
What strategy did you use to draw your shapes?