Name 17.1 ? Geometry and Measurement—3.7.B MATHEMATICAL PROCESSES 3.1.C, 3.1.E, 3.1.G Model Perimeter Essential Question How can you find perimeter? Hands On Investigate Investigate Perimeter is the distance around a figure. Materials ■ geoboard ■ rubber bands You can find the perimeter of a rectangle on a geoboard or on dot paper by counting the number of units on each side. A. Make a rectangle on the geoboard that is 3 units on two sides and 2 units on the other two sides. B. Draw your rectangle on the dot paper below. 1 Unit C. Write the length next to each side of your rectangle. D. Add the number of units on each side. _+_+_+_=_ © Houghton Mifflin Harcourt Publishing Company E. So, the perimeter of the rectangle is _ units. • How would the perimeter of the rectangle change if the length of two of the sides was 4 units instead of 3 units? Module 17 545 Make Make Connections Connections Math Talk You can also use grid paper to find the perimeter of figures by counting the number of units on each side. Start at the arrow and trace the perimeter. Begin counting with 1. Continue counting each unit around the figure until you have counted each unit. A Mathematical Processes If a rectangle has a perimeter of 12 units, how many units wide and how many units long could it be? Explain. B 1 1 1 Unit 1 Unit Perimeter = _ units Perimeter = _ units Share Share and and Show Show Hands On Find the perimeter of the figure. Each unit is 1 centimeter. 2. _ centimeters 546 _ centimeters © Houghton Mifflin Harcourt Publishing Company 1. Name Problem Problem Solving Solving Multi-Step What’s the Error? 3. Kevin is solving perimeter problems. He counts the units and says that the perimeter of this figure is 18 units. Look at Kevin’s solution. A Find Kevin’s error. B 18 17 1 16 15 2 14 3 13 4 12 5 11 6 7 8 9 10 Perimeter = 18 units Perimeter = _ units • Use the grid on the right to find the correct perimeter of © Houghton Mifflin Harcourt Publishing Company the figure above. 4. Apply Describe the error Kevin made. 5. Use Diagrams Circle the places in the drawing of Kevin’s solution where he made an error. 6. Write Math Explain how to find the length of each side of a triangle with sides of equal length, and a perimeter of 27 inches. Module 17 • Lesson 1 547 Mathematical Processes M Model ¥ Reason ¥ Communicate M Daily Daily Assessment Assessment Task Task Fill in the bubble completely to show your answer. 7. 8. Joseph drew a game court on grid paper. Each unit is 1 meter. What is the perimeter of the game court? A 18 meters C 16 meters B 15 meters D 8 meters Game Court 1 meter Val is designing a dog park. She needs to find the length for a fence around the park. Each unit is 1 yard. What is the perimeter of the park? A 29 yards C 47 yards B 32 yards D 34 yards Park 1 yard Multi-Step Greg is framing two rectangular paintings. One painting has side lengths of 3 inches and 9 inches. The other painting has side lengths of 4 inches and 6 inches. How many inches of framing material will Greg need for the two paintings? A 48 inches C 22 inches B 51 inches D 44 inches TEXAS Test Prep 10. 548 Naomi drew this design for a quilt block. What is the perimeter of the design? A 12 units C 14 units B 16 units D 18 units © Houghton Mifflin Harcourt Publishing Company 9. Geometry and Measurement—3.7.B MATHEMATICAL PROCESSES 3.1.C, 3.1.E, 3.1.G H o mewo rk and Practice 17.1 Name Model Perimeter Find the perimeter of the figure. Each unit is 1 centimeter. 1. 2. _ centimeters _ centimeters Problem Problem Solving Solving 3. Alyssa says the perimeter of this figure is 13 units. Describe the error Alyssa made. Draw your own figure on the grid. Find the perimeter. 10 13 1 4. 9 12 11 2 8 3 4 5 6 7 © Houghton Mifflin Harcourt Publishing Company Perimeter = _ units Module 17 • Lesson 1 549 TEXAS Test Prep Lesson Lesson Check Check Fill in the bubble completely to show your answer. 6. 7. 550 Paula drew this plan for a new backyard shed. Each unit is 1 foot. What is the perimeter of the shed? A 24 feet B 20 feet C 18 feet D 42 feet Shed 1 foot Andy drew this plan for a fence in his yard. Each unit is 1 meter. What is the perimeter of the fence? A 18 meter B 24 meter C 22 meter D 36 meter Multi-Step Latoya sews a border around two quilts. One quilt has side lengths of 4 feet and 6 feet. Another quilt has side lengths of 8 feet and 6 feet. How many feet of border does she sew? A 28 feet B 20 feet C 48 feet D 42 feet Fence 1 meter 8. Multi-Step Roland buys baseboards for two rectangular rooms. One room has side lengths of 5 meters and 7 meters. The second room has side lengths of 6 meters and 9 meters. How many meters of baseboard does Roland buy? A 50 meters B 30 meters C 24 meters D 54 meters © Houghton Mifflin Harcourt Publishing Company 5.

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