Module 7 Lesson 15Solve word problems to determine perimeter with given side lengths.

Multiply by 9 PATTERN SHEET

2 minutes

End

Multiply by 7

7 x 9 = _______

Let’s skip count by 9.

9 18 27 36

54

45

63 72 81 90

9 x 9 = _______

6 x 9 = _______

8 x 9 = _______

Equivalent Counting with Units of 5

5 10 15 20 25

30 35 40 45 50

1 five 2 fives 3 fives 4 fives 5 fives

6 fives 7 fives 8 fives 9 fives 10 fives

We’re going to count by fives to 503 x 5 = 15 5 x 5 = 25

8 x 5 = 40

Now count groups of five. When I say “Stop!,” stop and say the multiplication sentence.

Find the Perimeter

What is the perimeter of this

shape?

4 x 7 = 28 in.

7 in

Find the Perimeter

What is the perimeter of this

shape?

4 + 4 + 4 + 5 + 512 + 10 = 22 ft.

4 ft 4 ft

4 ft

5 ft 5 ft

Find the Perimeter

What is the perimeter of this

shape?

(2 x 3) + (2 x 4)= 6 + 8 =14 cm

4 cm

4 cm

3 cm3 cm

Find the Perimeter

What is the perimeter of this

shape?

8 + 6 + 10 = 24 ft

8 ft

6 ft10 ft

Find the Perimeter

What is the perimeter of this

shape?

(4 x 5) + (8 x 2)= 20 + 16 = 36 cm

5 cm

2 cm 2 cm

2 cm

2 cm

2 cm

2 cm

2 cm2 cm

5 cm

5 cm 5 cm

Problem of the Day

Clara and Pedro each use four 3-inch by 5-inch cards to make the rectangles below. Whose rectangle has a greater perimeter?

Pedro’s Rectangle

Clara’s Rectangle

3 in

5 in

5 in

3 in

Perimeter of Clara’s rectangle:(8 x 5) + (2 x 3) = 46 in

Perimeter of Pedro’s rectangle:(4 x 5) + (4 x 3) = 32 in

Clara’s Rectangle has

the greater perimeter:

46 inches.

Problem solving steps

1. Read & Model the problem• Read the problem• What can you draw?• What conclusions can you make using the drawing?

2. Write & Solve an equation• Use numbers to show your thinking and conclusions

3. Write a statement explaining your answer• Use words to explain your answer and how it relates to the problem

4. Assess the reasonableness of your solution• Ask yourself questions to make sure your answer makes sense:

• The question asks for …• My answer matches the question because …• The units I used make sense because …• My answer is the right size (not too big or small) because …

Problem 1

Mrs. Kozlow put a border around a 5-foot by 6-foot rectangular bulletin board. How many feet of border did Mrs. Kozlow need?

Mrs. Kozlow used 22 feet of border.

What can we draw to help solve this question?

What is the question asking?

A rectangle with sides lengths labeled!

Write a number sentence:

6 + 6 + 5 + 5 = 22 ft

Mrs. Kozlow put a border around a 5-foot by 6-foot rectangular bulletin board. How many feet of border did Mrs. Kozlow need?

6 ft

6 ft

5 ft 5 ft

Problem 2

Jason built a model of the Pentagon for a social studies project. He made each outside wall 33 centimeters long. What is the perimeter of Jason’s model Pentagon?

The perimeter of the model pentagon is 165 cm.

What can we draw to help solve the problem?

Jason built a model of the Pentagon for a social studies project. He made each outside wall 33 centimeters long. What is the perimeter of Jason’s model Pentagon?

What is the question asking?

We can draw & label a pentagon to help us solve the problem.

Write a number sentence:5 x 33 = p

33 cm

(5 x 30) + (5 x 3) = 150 + 15 = 165 cm

Problem Set