Primary 3 Area and Perimeter
Area measures the region enclosed by a shape, in square units such as cm² or m². Perimeter is the total length of the shape's boundary, measured in units of length such as cm or m.
Keywords
- Area
- The amount of flat space inside a shape.
- Perimeter
- The distance around the outside of a shape.
- Square unit
- One equal square used to measure area.
- Square centimetre
- The area of a 1 cm by 1 cm square, written cm².
- Square metre
- The area of a 1 m by 1 m square, written m².
Measure area in square units
Arrange equal unit squares within the boundary without gaps or overlaps. The number of unit squares gives the area in square units.
A figure has 4 columns and 3 rows of equal unit squares. What is its area?
See worked example
A rectangular figure has 3 rows of 4 unit squares. What is its area?
- Each row contains 4 unit squares.
- There are 3 rows: 3 × 4 = 12.
- Area = 12 square units.
Answer: 12 square units
Try together
A rectangular figure has 2 rows of 6 unit squares. What is its area?
Reveal the answer
2 × 6 = 12 square units.
Measure area in cm²
A square with side length 1 cm has an area of 1 cm². For a rectangle, area = length × breadth.
A card is 5 cm long and 3 cm wide. What is its area in cm²?
See worked example
A card is 5 cm long and 3 cm wide. What is its area?
- Each unit square has an area of 1 cm².
- There are 3 rows of 5 unit squares: 5 × 3 = 15.
- Area = 15 cm².
Answer: 15 cm²
Try together
What is the area of a card measuring 6 cm by 2 cm?
Reveal the answer
12 cm², because 6 × 2 = 12.
Measure area in m²
A square with side length 1 m has an area of 1 m². A rectangle's area is length × breadth, expressed in m² when both dimensions are in metres.
A floor is 4 m long and 3 m wide. What is its area in m²?
See worked example
A floor is 4 m long and 3 m wide. What is its area?
- Each unit square has an area of 1 m².
- There are 3 rows of 4 unit squares: 4 × 3 = 12.
- Area = 12 m².
Answer: 12 m²
Try together
A small floor is 5 m long and 2 m wide. What is its area?
Reveal the answer
10 m², because 5 × 2 = 10.
Area and perimeter of a square
A square has four equal side lengths. Area = side length × side length. Perimeter = the sum of its four side lengths.
A square has sides of 5 cm. Find its area and perimeter.
Choose area or perimeter, then show the first step.
See worked example
Find the area and perimeter of a square with sides of 5 cm.
- Area = 5 × 5 = 25 cm².
- Perimeter = 5 + 5 + 5 + 5 = 20 cm.
Answer: Area = 25 cm²; perimeter = 20 cm.
Try together
A square has sides of 6 cm. Find its area and perimeter.
Reveal the answer
Area = 6 × 6 = 36 cm². Perimeter = 6 + 6 + 6 + 6 = 24 cm.
Area and perimeter of a rectangle
A rectangle has two pairs of equal opposite sides. Area = length × breadth. Perimeter = length + breadth + length + breadth.
A rectangle is 8 cm long and 3 cm wide. Find its area and perimeter.
Choose area or perimeter, then show the first step.
See worked example
Find the area and perimeter of a rectangle 8 cm long and 3 cm wide.
- Area = 8 × 3 = 24 cm².
- Perimeter = 8 + 3 + 8 + 3 = 22 cm.
Answer: Area = 24 cm²; perimeter = 22 cm.
Try together
A rectangle is 7 cm long and 4 cm wide. Find its area and perimeter.
Reveal the answer
Area = 7 × 4 = 28 cm². Perimeter = 7 + 4 + 7 + 4 = 22 cm.