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3rd grade

Course: 3rd grade > Unit 10

Lesson 4: Multiply to find area
Math
3rd grade
Area
Multiply to find area
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Area of rectangles review

Google Classroom
Review the basics of area of rectangles and try some practice problems.

What is area?

Area is the space inside of a two-dimensional shape. We can also think of area as the amount of space a shape covers.
For example, the rectangle below has an area of 12 square units because it covers 12 square units.
A rectangle with 2 rows. Each row has 6 unit squares. The unit squares are labeled 1 through 12.
Want to learn more about the concept of area? Check out this video.

Area of a rectangle formula

To find the area of a rectangle, we multiply the length of the rectangle by the width of the rectangle.
Area of rectangle=length×width
Want to know why this formula works? Check out this video.

Example 1:

A rectangle with 2 rows. Each row has 6 unit squares. The left side of the rectangle is labeled 2 units and the top side of the rectangle is labeled 6 units.
Area=length×width
Area=6×2
Area=12 square units

Example 2:

A rectangle with the left side labeled 4 units and the top side labeled 7 units.
Area=length×width
Area=7×4
Area=28 square units

Practice set 1: Multiply to find area

Problem 1A
What is the area of the rectangle?
A rectangle with the left side labeled 6 units and the top side labeled 5 units.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
square units

Want to try some more area of rectangle problems? Check out this exercise:
Area of rectangles

Practice set 2: Count square units to find area

Problem 2A
What is the area of the shape? Each square in the grid is a 1×1 unit square.
A figure with 4 rows and 4 columns of 11 unit squares connected together on a grid. The top 2 rows each have 4 unit squares. The third row has 2 unit squares. The bottom row has 1 unit square.
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
square units

Want to try some more unit square problems? Check out these exercises:
Find area by counting unit squares
Transition from unit squares to area formula
Create rectangles with a given area

Practice set 3: Challenge items

Problem 3A
This cat and bird picture has an area of 56 square centimeters. The height of the picture is 7 centimeters.
What is the width of the picture?
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
centimeters
A rectangular picture of a cat and a bird. The left side of the picture is labeled 7 centimeters and the top side of the picture is labeled width.

Want to try some more challenge items? Check out these exercises:
Find a missing side length when given area
Decompose figures to find area 1
Decompose figures to find area 2

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