Grade 4 Mathematics Measurement – Area Notes
Mathematics — Measurement
Subtopic: Area (For learners aged 9 — Kenya)
What is area?
Area is the amount of space inside a flat shape (for example a rectangle or square). We measure area using square units (little squares). For example: square centimetres (cm²) or square metres (m²).
Example: Count the little squares
Count the blue squares: 3 rows × 3 columns = 9 little squares. So area = 9 square units (9 cm² if each small square is 1 cm by 1 cm).
Square units
A square centimetre (1 cm²) is a square 1 cm long and 1 cm wide. We use many of these little squares to fill a shape and find its area.
1 cm²
If a rectangle is 4 cm by 3 cm: area = 4 × 3 = 12 cm².
Area of a rectangle
Formula: Area = length × width
Example: A classroom carpet is 5 cm by 3 cm on our tiny model.
Area = 5 × 3 = 15 square units → 15 cm² (if each small square is 1 cm²).
Area of a square
A square has all sides equal. Formula: Area = side × side = side². Example: side = 4 cm → area = 4 × 4 = 16 cm².
Units and a simple conversion
Common area units: cm² (small things), m² (bigger things like a classroom floor). 1 m = 100 cm, so 1 m² = 100 cm × 100 cm = 10 000 cm².
So a small tile of 10 cm by 10 cm has area = 100 cm².
How to find area — quick steps
- Draw or imagine a grid of 1 cm by 1 cm squares over the shape.
- Count the little squares (use multiplication by rows × columns if it is a rectangle).
- Write the answer with square units (for example 20 cm²).
Practice — try these
- A rectangle has length 6 cm and width 2 cm. Find the area.
- A square has side 5 cm. Find its area.
- Count the squares: a shape has 4 rows and 4 columns filled. What is the area?
- A small garden is 2 m by 3 m. What is the area in m² and in cm²?
Answers
- Area = 6 × 2 = 12 cm².
- Area = 5 × 5 = 25 cm².
- Area = 4 × 4 = 16 square units (16 cm² if each square is 1 cm²).
- Area = 2 × 3 = 6 m². In cm²: 6 m² = 6 × 10 000 = 60 000 cm².
Helpful tips
- Use floor tiles or squared exercise books to make counting area easier.
- Check units: always include cm² or m² in your answer.
- Remember: area uses two dimensions (length and width), so the unit name has a little 2 (square).
Notes: These activities match basic Kenyan primary school ideas about area for learners around 9 years. Teachers can let pupils use rulers and squared paper to practise.