📐

Perimeter & Area of Rectangles

Use P = 2(l + w) and A = l × w to measure rectangles and solve real-world problems.

Bridge to Grade 6 Unit R5 ¡ Lesson 3 Builds 6.G.1
Lesson progress: 0%
Why this matters for Grade 6: In Grade 6 you find areas of triangles, quadrilaterals, and polygons by composing and decomposing shapes (6.G.1). Understanding how to find the perimeter and area of a rectangle is the foundation that all of those more complex formulas build on.
1
Learn It

Perimeter & Area Formulas

Perimeter is the distance around the outside of a shape. Add up all the sides.
Area is the amount of surface inside the shape. Count the square units.

Rectangle with length l and width w:
P = 2(l + w)  |  A = l × w
Example 1 — Rectangle 5 units × 3 units:
length = 5 w=3
P = 2(5 + 3) = 2 × 8 = 16 units
A = 5 × 3 = 15 square units
Example 2 — Word Problem:
A garden is 8 meters long and 4 meters wide. How much fencing is needed, and how much soil covers the garden?

Fencing = Perimeter = 2(8 + 4) = 2 × 12 = 24 meters
Soil coverage = Area = 8 × 4 = 32 square meters
2
Try It ¡ Guided

Work These Together

1. A rectangle is 7 cm long and 4 cm wide. What is its perimeter in cm?

Hint

P = 2(l + w) = 2(7 + 4) = 2 × 11 = 22 cm.

2. A rectangle is 7 cm long and 4 cm wide. What is its area in square cm?

Hint

A = l × w = 7 × 4 = 28 square cm.

3
Practice ¡ On Your Own

You Try

3. A classroom floor is 10 m long and 6 m wide. What is the area of the floor in square meters?

Hint

A = l × w = 10 × 6 = 60 square meters.

4. A picture frame needs trim around the outside. The frame is 12 in long and 9 in wide. How many inches of trim are needed (perimeter)?

Hint

P = 2(l + w) = 2(12 + 9) = 2 × 21 = 42 inches.

5. A rectangle has an area of 36 sq ft and a length of 9 ft. What is its width in feet?

Hint

A = l × w → 36 = 9 × w → w = 36 ÷ 9 = 4 feet.

★
Exit Ticket

Show What You Know

6. A rectangle is 11 m long and 5 m wide. What is its area in square meters?

Hint

A = 11 × 5 = 55 square meters.

7. A playground is 15 m long and 8 m wide. How much fencing (perimeter) is needed in meters?

Hint

P = 2(15 + 8) = 2 × 23 = 46 meters.

← Lesson 2: Rates & Unit Rates Next: Area of Triangles →

Neft Teacher ¡ Bridge to Grade 6 ¡ Unit R5 ¡ Lesson 3 ¡