Lesson 9 Measure to Find the Area

    • Let’s measure the sides of rectangles and find the area.

Warm-up Notice and Wonder: Groups and Arrays

What do you notice? What do you wonder?

6 groups of 3 dots. 15 black dots, 3 blue dots.
Rectangular array of dots. 6 groups of 3 dots. 15 black dots, 3 blue dots. 

Activity 1 Measure to Find Area

Picture of ruler. Scale, 0 to 8, by 1's. 4 tick marks between each unit.

Use a ruler to measure the rectangles. Then, calculate the area of the rectangles in square centimeters.

  1. a rectangle.
  2. a rectangle.
  3. A rectangle.

Activity 2 Create a Rectangle

Your teacher will give you some tape. Use it to create a rectangle with your assigned area.

  • Area 1: 4 square feet

  • Area 2: 6 square feet

  • Area 3: 9 square feet

  • Area 4: 10 square feet

  • Area 5: 12 square feet

  • Area 6: 16 square feet

Practice Problem

Problem 1

  1. Use your ruler to find the area of the rectangle in square centimeters.

    A rectangle.

  2. Use your ruler to draw a rectangle whose area is 18 square centimeters.