This grade 4 area perimeter lesson explains area and perimeter of rectangles in one printable page, with definitions, a method and a worked example.
Area is the amount of flat space inside a shape, and perimeter is the distance around it. For a rectangle, area equals length times width, and perimeter equals twice the length plus twice the width. An 8 foot by 5 foot rectangle has an area of 40 square feet.
Grade 4 Area Perimeter Lesson: key facts
- Area of a rectangle: A = l × w, in square units
- Perimeter of a rectangle: P = 2 × l + 2 × w, in plain units
- A square has area s × s and perimeter 4 × s
- To find a missing side from area, divide by the known side
- Rectangles with the same perimeter can have different areas
What are area and perimeter?
Area tells how much flat space a shape covers. Perimeter tells how far it is around the edge. Think of a garden: the grass inside is the area, and the fence around it is the perimeter.
Area is measured in square units, such as square feet. Perimeter is measured in plain units, such as feet. A rectangle has two long sides (length) and two short sides (width).
How do you find the area of a rectangle?
Cover the rectangle with unit squares. A rectangle that is 6 units long and 4 units wide has 4 rows of 6 squares.
Counting every square works, but multiplying is faster:
\(A = l \times w\)
How do you find the perimeter of a rectangle?
Add the lengths of all four sides. Opposite sides are equal, so you can also add the length and width and then double the sum.
\(P = 2 \times l + 2 \times w\). For this rectangle, \(2 \times 8 + 2 \times 5 = 16 + 10 = 26\).
How do you find a missing side?
Use the formula backward. If the area and one side are known, divide. A rectangle has an area of 48 square feet and a width of 6 feet. Find its length.
- Write the multiplication: \(l \times 6 = 48\).
- Divide: \(48 : 6 = 8\).
- Check: \(8 \times 6 = 48\).
Can two rectangles have the same perimeter but different areas?
Yes. Both rectangles below have a perimeter of 16 units, but their areas are different. Do not mix up the two measures.
Area and Perimeter of Rectangles: frequently asked questions
What is the formula for the area of a rectangle?
The area of a rectangle is length times width, written A = l × w. A rectangle 9 feet long and 4 feet wide has an area of 36 square feet.
What is the formula for the perimeter of a rectangle?
The perimeter is 2 × l + 2 × w, or add all four sides. For a 7 inch by 3 inch rectangle, the perimeter is 14 + 6 = 20 inches.
Why is area measured in square units?
Area counts how many unit squares cover a shape, and each square is one unit long and one unit wide. That is why the answer is in square feet or square inches.
How do I find a missing side of a rectangle?
If you know the area, divide it by the known side. If you know the perimeter, divide it by 2 and then subtract the known side.
Can a square use the same formulas?
Yes. A square is a rectangle with equal sides. Its area is side times side, and its perimeter is 4 times the side length.
How to use this grade 4 area perimeter lesson
Use this grade 4 area perimeter lesson before the worksheet, then check what you learned with the quiz.
See every chapter on the Grade 4 math page.