Grade 5 Mathematics Measurement – Area Notes
Mathematics — Measurement
Subtopic: Area (For learners aged about 10 years)
What is area?
Area tells us how much surface a flat shape covers. It is measured in square units. Think of covering a tabletop with square tiles — the number of tiles needed is the area.
Square units (units of area)
Common units: square centimetre (cm²), square metre (m²). One square metre (1 m²) is a square that is 1 m long and 1 m wide.
Remember: 1 m = 100 cm, so 1 m² = 100 cm × 100 cm = 10 000 cm²
Area of a rectangle or square
For rectangles and squares use: Area = length × width. - For a square both sides are the same so Area = side × side = side².
How many unit squares?
Count the small squares: 4 across and 3 down → 4 × 3 = 12 squares.
Area = 12 m²
Worked examples
Example 1: A rectangle has length 6 m and width 2 m. Find the area.
Area = length × width = 6 × 2 = 12 → area = 12 m².
Example 2 (square): A square has side 5 cm. Find the area.
Area = side² = 5 × 5 = 25 → area = 25 cm².
Example 3 (convert units): Convert 3 m² to cm².
1 m² = 10 000 cm² so 3 m² = 3 × 10 000 = 30 000 cm².
Area of a triangle (simple)
For a triangle: Area = 1/2 × base × height. The height is the straight line at right angles to the base.
Example: Triangle with base 8 cm and height 3 cm.
Area = 1/2 × 8 × 3 = 4 × 3 = 12 cm².
How to find area for odd shapes
- Draw a grid of unit squares and count full squares.
- For half squares, combine them to make full squares.
- Or split the shape into rectangles and triangles, find each area, then add.
Practice (Try these)
- Find the area of a rectangle 7 m by 4 m.
- Find the area of a square with side 9 cm.
- Convert 25 m² to cm².
- Find the area of a triangle with base 10 cm and height 6 cm.
- A small garden is 5 m by 3 m. How many 1 m by 1 m tiles are needed to cover it?
Answers below — try first on your own.
Answers to Practice
- 7 × 4 = 28 → 28 m²
- 9 × 9 = 81 → 81 cm²
- 25 m² = 25 × 10 000 = 250 000 cm²
- Area = 1/2 × 10 × 6 = 5 × 6 = 30 cm²
- Tiles needed = 5 × 3 = 15 tiles (each 1 m²) → 15 m²