AA.1 Use formulas to find the area of rectangles
What is area?
Area is the amount of space inside a flat shape. It tells us how much surface a shape covers. Area is measured in square units, such as square inches (in²) or square centimeters (cm²).
- A rectangle drawn on grid paper covers 12 squares. Its area is 12 square units.
Think of area as "how many little squares fit inside the shape."
How to find the area of a rectangle
The formula for the area of a rectangle is:
Area = length × width
- Measure the length of the rectangle.
- Measure the width of the rectangle.
- Multiply the length by the width.
- Write the answer with the correct square unit (such as cm² or in²).
Always use the same unit for length and width. Multiply, then label your answer with square units.
How to find the area of a square
A square is a special rectangle with all sides equal. The formula for area is:
Area = side × side or Area = side²
- If each side of a square is 5 cm, then area = 5 × 5 = 25 cm².
Since all sides are equal, you only need one measurement to find the area of a square.
Identifying when to use the area formula
Use the area formula when you are asked about the space inside a rectangle or square, not just the distance around it.
- If you need to know how much carpet covers a rectangular room → use area.
- If you want to know how many tiles fill a square floor → use area.
Do not confuse area with perimeter. Perimeter measures the distance around a shape, while area measures the space inside.
Practice with full sentences
Writing about math helps show understanding. Use full sentences to explain your work.
- “The rectangle is 8 cm long and 3 cm wide. The area is 8 × 3 = 24 cm².”
- “The square has sides of 6 inches. The area is 6 × 6 = 36 in².”
Always include the unit and show how you multiplied. This makes your answer complete and correct.