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The customary system is another system of measurement used in the United States to describe how long, how heavy, or how big something is. 


Inch, foot, yard, and mile are units for measuring area, perimeter, and volume. 


12 inches (in) = 1 foot (ft)
3 feet = 1 yard (yd)
5280 feet = 1 mile (mi)


The area of a figure is the number of square units needed to cover it.

Count the number of square units to find the area. Area = 9 square in.
You can also find the area of a square or rectangle by using a formula.

Area = length x width

Area = 3 x 3

Area = 9 square in.


Perimeter is the word used to describe the distance around the outside of an object or shape. To find the perimeter of any shape, add the lengths of its sides.

When two pairs of sides are the same length, multiply 2 times the length and 2 times the width. Then add the products.

( 2 x 10 ft. ) + ( 2 x 4 ft.) =

20 ft. + 8 ft. = 28 ft.

When all the sides are the same length, multiply the number of sides times the length of one side.
4 sides x 3 yd Perimeter  4 x 3 = 12 yd

When the lengths of the sides are different, add the lengths of the sides.
5 in. + 10 in. + 7 in. = Perimeter: 22 in.


The Volume of a solid is the number of cubic units it contains.

 This is one cubic unit

Find the cubic measure by counting the cubes.

5 cubic units

You can also find the volume of a rectangular prism by using a formula.

Volume = length x width x height

Volume = 4 in. x 2 in. x 5 in.

Volume = 40 cubic in.

Let's Practice!
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Use square units, a 2-dimensional measure, to talk about area.

Use cubic units, a 3-dimensional measure, to talk about volume.

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