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Year 3 Maths Measurement

Area

Area is the amount of space inside a 2D shape. We measure it in square units (cm², m²). For rectangles, we can use the formula: Area = length × width.

Area by Counting Squares

Count each unit square inside the shape. Each square = 1 cm² (or 1 square unit).

1
2
3
4
5
6
7
8
9
10
11
12

Area = 12 cm²

Area = Length × Width

For rectangles, multiply the length by the width instead of counting every square.

A rectangle: 5 cm long, 3 cm wide

5 × 3 = 15 cm²

Area = length × width

Square Centimetres (cm²)

We write area in square centimetres (cm²) or square metres (m²).

  • 📚 Book cover: about 600 cm²
  • 🆕 Bedroom floor: about 12 m²
  • 💧 Postage stamp: about 4 cm²

The ² means "squared" — it is a 2D measurement.

Area vs Perimeter

Area

Space inside a shape. Measured in cm², m².

Perimeter

Distance around the outside. Measured in cm, m.

Worked Example

A school garden bed is 6 m long and 4 m wide. What is the area?

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Step 1: Identify length and width. Length = 6 m, Width = 4 m

Step 2: Use the formula. Area = length × width

Step 3: Calculate. Area = 6 × 4 = 24 m²

The garden bed has an area of 24 m².

Length: 6 m
Width: 4 m
Area: 24 m²

Key Vocabulary

area — the amount of space inside a flat shape
cm² — square centimetre; the unit for measuring small areas
formula — a rule written using symbols: Area = length × width
perimeter — the total distance around the outside edge of a shape

Knowledge Check

Question 1

A rectangle is 7 cm long and 3 cm wide. What is its area?

Question 2

A square has a side length of 5 cm. What is its area?

Question 3

A classroom floor is 8 m long and 6 m wide. What is the area of the floor?

Question 4

Two rectangles: Rectangle A is 4 cm × 5 cm. Rectangle B is 3 cm × 7 cm. Which has the larger area?

Lesson Summary