5th Grade Math: How to Find the Area of a Shape

Finding the Area of a Shape

When you get to 6th grade, you'll learn to calculate the areas of shapes, like triangles and special quadrilaterals, but for now you just need to find the areas of rectangles. Remember that area is the amount of 2-dimensional space that a shape takes up, and a rectangle is a shape that has four right angles and two sets of parallel sides. The formula for finding the area of a rectangle is Area = (Length) x (Width).

Units for Area

Area is reported in square units, like square inches, square centimeters and square feet. Whatever units the length and width of your rectangle are measured in, your answer will be in those units squared. For instance, if your rectangle is five meters long and four meters wide, its area will be 20 square meters, since both the length and width are measured in meters.

Tip: Be sure that your rectangle's length and width are measured in the same units. If they're not, you'll need to convert the units so they're the same.

Practice Problems

1. Your classroom is 20 feet long and ten feet wide. Find the area.
2. If you want to build a brick wall that's ten bricks tall and 100 bricks wide, how many bricks will you need?
3. The door to Sandra's house is three meters tall and 100 centimeters wide. What is its area? Express your answer in square meters.
4. Fatima's garden has an area of 25 square yards and a length of five yards. What is the width of Fatima's garden?
5. Alex has a blue piece of poster board with a length of ten centimeters and a width of 12 centimeters. He also has a yellow piece with a length of 12 centimeters and a width of eight centimeters. Which piece has a greater area, the blue one or the yellow one?

Answer Key

1. Use the formula Area = (Length) x (Width). Since the classroom is 20 feet long and ten feet wide, multiply 20 feet by ten feet to get the area of 200 square feet (20 x 10 = 200).
2. The wall's length is 100 bricks, and its height is ten bricks. Since 100 x 10 = 1,000, it will take 1,000 bricks to build it.
3. First, convert 100 centimeters to meters. Since 100 cm = 1 m, Sandra's door is one meter wide. Now, multiply the length by the width (3 x 1) to get the area of three square meters.
4. Since you know that the length is five yards and the area is 25 square yards, you need to solve the equation 5 x ? = 25. Since 5 x 5 = 25, Fatima's garden is five yards wide.
5. The area of the blue piece is 120 square centimeters, since 10 x 12 = 120. The yellow piece has an area of 96 square centimeters, since 12 x 8 = 96. The blue piece of poster board has the greater area because 120 cm > 96 cm.