Primary 4 Area and Perimeter
Keywords
- Area
- The space inside a shape, measured in square units such as cm².
- Perimeter
- The distance around the outside, measured in units such as cm.
- Composite figure
- A figure made by joining simpler shapes.
- Side length
- The distance along one edge.
Find the length of one side of a square given its area or perimeter
All four sides of a square are equal. Given its area, find the equal side length that multiplies by itself to make the area. Given its perimeter, divide by four.
Find the side length of the square
Choose an example, then show the first step.
Try together
A square has area 49 cm². What is one side? A different square has perimeter 32 cm. What is one side?
Reveal the answer
7 cm because 7 × 7 = 49; 8 cm because 32 ÷ 4 = 8.
Find the area and perimeter of composite figures made of rectangles and squares
Split a composite figure into rectangles or squares to find its area. For perimeter, follow only its outside boundary; an internal joining line does not count.
Two ways to build a composite figure
Choose an example, then show the first step.
Try together
A T-shape has a 10 cm by 2 cm top rectangle and a centred 4 cm by 4 cm square stem. Find its area and perimeter.
Reveal the answer
Area = 10 × 2 + 4 × 4 = 36 cm². Perimeter = 10 + 2 + 3 + 4 + 4 + 4 + 3 + 2 = 32 cm.