Unit 7, Lesson 18-- Finding Perimeter Using Addition

Lesson 18-- Finding Perimeter Using Addition

Introduction

Hello Mathematicians! Today we will be learning about using addition to find the perimeter of a shape.

Consider the following situation:

Jane’s class is building a robot for a competition. The robot must follow a path around a figure one time. The robot must travel at least 25 units to go to the next round. Which path should Jane’s class choose to go to the next round? 

190531.pngTrapezoid, side lengths 10, 6, 5, 6. Rhombus, side lengths 6, 6, 6, 6.

In your math notebook, show your thinking about which path Jane’s class should choose and why. 

Interactive Visual

Remember: perimeter is the measure of length around all the outside edges of a shape. Sometimes, we are given defined length units, like inches, feet, yards, or miles.

Interactive

Part 1 Directions:

  • In the interactive below, find the perimeter of the shapes by adding all of the side lengths.  Then, find the matching perimeter total card.

Part 2 Directions:

  • Complete the Robot Racing challenge below.
  • Show your work in your math notebook, using drawings, numbers, and words.

Robot-Racing-SR-Grade-3-Unit-7 PDF Download Robot-Racing-SR-Grade-3-Unit-7 PDF

In Your Math Notebook

Let’s get out our math journals and  work through the following application problem. Make sure you read the problem carefully, draw a picture to match your thinking and write and solve an equation.

Read, Draw, Write, DONE!

R (Read the problem carefully.)

Jane's class drew a robot path with a pentagon with a path (perimeter) of  30 units.  What could it have looked like?

D (Draw a picture.)

W (Write and solve an equation.)

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Georgia Department of Education, Math