Lesson 13 Perimeter and Area of Rectangles

    • Let’s explore the perimeter and area of rectangles on the coordinate grid.

Warm-up Estimation Exploration: Window Washing

What is the area of one window?

photograph of window washers and windows. Each window, width, about man's arm span, height, about one and one half man's height.  

Record an estimate that is:

too low

about right

too high

Activity 1 Rectangle Perimeters

length (cm)

width (cm)

Coordinate plane. Horizontal axis, length in centimeters, 0 to 10, by 1's. Vertical axis, width in centimeters, 0 to 10, by 1's. 

  1. Jada drew a rectangle with a perimeter of 12 centimeters. What could the length and width of Jada’s rectangle be? Use the table to record your answer.

  2. Plot the length and width of each rectangle on the coordinate grid.

  3. If Jada drew a square, how long and wide was it?

  4. If Jada’s rectangle was 2.5 cm long, how wide was it? Plot this point on the coordinate grid.

  5. If Jada’s rectangle was 3.25 cm long, how wide was it? Plot this point on the coordinate grid.

Activity 2 Rectangle Areas

length (cm)

width (cm)

Coordinate plane. Horizontal axis, length in centimeters, 0 to 16, by 1's. Vertical axis, width in centimeters, 0 to 16, by 1's. 

  1. Jada drew a rectangle with area 16 square centimeters. What could the length and width of Jada’s rectangle be? Use the table to record your answer.

  2. Plot the length and width of each rectangle on the coordinate grid.

  3. If Jada’s rectangle was 5 cm long, how wide was it? Plot this point on the coordinate grid.

  4. If Jada’s rectangle was 3 cm long, how wide was it? Plot this point on the coordinate grid.

  5. If Jada drew a square, how long and wide was it? Explain how you know.

Practice Problem

Problem 1

Coordinate plane. Horizontal axis, length in centimeters, 0 to 10, by 1's. Vertical axis, width in centimeters, 0 to 10, by 1's. point at 3 comma 7. 

  1. The point on the graph shows the length and width of a rectangle. What is the perimeter of the rectangle?

  2. Plot 4 more points for different rectangles with the same perimeter as the given rectangle.

  3. Which point would represent a square with the same perimeter as the given rectangle?