Virginia SOL Math / Grade 3 / Measurement & Geometry

3.MG.2

Area & Perimeter

What you'll learn

  • Measure area by counting square units
  • Find the perimeter by adding side lengths
  • Solve problems in context involving area and perimeter

Words to know

Area —
the number of square units that cover a shape
Perimeter —
the distance all the way around a shape
Square unit —
one unit-by-unit square used to measure area
Side length —
how long one side of a shape is

Why it matters Area tells us how much space a floor or garden covers; perimeter tells us how much fence or border we need around it.

Worked examples

Model ItI do

Find the area and perimeter of this rectangle.

Area: count the squares, 5 × 3 = 15 square units. Perimeter: add the sides, 5 + 3 + 5 + 3 = 16 units.

Try It TogetherWe do

A square rug has sides of 4 feet. What is its perimeter?

A square has 4 equal sides: 4 + 4 + 4 + 4 = 16 feet. (Or 4 × 4 = 16 feet.)

Now YouYou do

A rectangle is 6 units long and 2 units wide. Find its area.

Multiply length by width, or count squares. Check your answer in the back.

Practice

Mastered 0 of 11

Warm-up

Ease in with the basics.

  1. 1.Find the area of a rectangle that is 5 units by 2 units.

  2. 2.Find the perimeter of a rectangle 6 units by 3 units.

  3. 3.Which measures the space that covers a shape: area or perimeter?

On Level

The core Quick Check from the book.

  1. 1.Find the area of a rectangle that is 4 units by 3 units.

  2. 2.Find the perimeter of a rectangle 7 units by 2 units.

  3. 3.A square has sides of 5 cm. What is its area?

  4. 4.Which measures the distance around a shape: area or perimeter?

  5. 5.A garden is 8 ft by 5 ft. How much fence goes around it?

Challenge

Stretch your thinking.

  1. 1.A square garden has sides of 9 feet. Find its area and its perimeter.

  2. 2.A rectangle has an area of 24 square units and a length of 6 units. What is its width?

  3. 3.A rectangular rug is 8 feet long and 4 feet wide. How much braid is needed to go all the way around it?