Area of rectangles
Use length × width with arrays and grid paper.
Quick answer
The area of a rectangle is found by multiplying its length by its width. You can also count squares on grid paper to find the area.
Learning outcome
By the end of this page, you will be able to find the area of any rectangle by multiplying its length and width, and you will understand how to use grid paper to count squares to find area.
- You can draw rectangles and label their length and width.
- You can multiply length by width to find the area.
- You can use grid paper to count squares to check your answer.
- You can apply this to real-life situations like finding the area of a garden or a book cover.
Why this matters
Knowing how to find the area of a rectangle helps you solve many real-life problems. For example, if you want to buy carpet for your bedroom, you need to know the area of the floor. If you're planning a garden, you need to know how much space you have. In games and art, you might need to know how much space a picture or building takes up. Understanding area helps you think about space and how to use it well.
How it works
Area is the amount of space inside a shape. For rectangles, you can find the area by multiplying the length and width. Here’s how:
- Measure the length of the rectangle (the longer side).
- Measure the width of the rectangle (the shorter side).
- Multiply the length by the width.
- Write the answer with the correct unit, like square centimetres (cm²) or square metres (m²).
Another way to find the area is to use grid paper. You can draw a rectangle and count how many squares fit inside it. Each square is one unit of area.
Examples you can see
Let’s look at some examples to make this clear:
Example 1: A simple rectangle
Imagine a rectangle that is 5 cm long and 3 cm wide.
Area = length × width
Area = 5 cm × 3 cm = 15 cm²
Example 2: Using grid paper
Draw a rectangle that is 4 squares long and 3 squares wide on grid paper.
Count the squares inside the rectangle: 4 × 3 = 12 squares.
The area is 12 square units.
Example 3: Real-life rectangle
Your bedroom is 4 metres long and 3 metres wide.
Area = 4 m × 3 m = 12 m²
Your bedroom floor covers 12 square metres.
Example 4: A garden
You have a garden that is 6 metres long and 4 metres wide.
Area = 6 m × 4 m = 24 m²
Your garden covers 24 square metres.
Try it as a mini adventure
Imagine you are a builder working on a new playhouse. You need to find the area of the floor to know how much carpet to buy. You measure the floor and find it is 5 metres long and 3 metres wide.
What is the area of the floor?
Area = 5 m × 3 m = 15 m²
You need to buy 15 square metres of carpet.
Now, try this challenge:
- Draw a rectangle that is 6 squares long and 2 squares wide on grid paper.
- Count the squares inside.
- Find the area by multiplying 6 × 2.
- Compare your two answers.
Did you get the same answer? Great job!
Common mistakes
- Mistake: Forgetting to write the unit squared (cm² or m²).
- Why it happens: Children may think the unit is just cm or m, not cm².
- Fix: Always remember to write the unit with a small 2, like cm².
- Mistake: Confusing length and width.
- Why it happens: It can be hard to tell which side is longer or shorter.
- Fix: Label the sides clearly and double-check which is the long side and which is the short side.
- Mistake: Using the wrong units in multiplication.
- Why it happens: Mixing up centimetres and metres.
- Fix: Always make sure both measurements are in the same unit before multiplying.
Parent and carer guide
Help your child understand the area of rectangles by:
- Using everyday objects like books, boxes, or tables to measure and find area.
- Playing with grid paper to draw rectangles and count squares.
- Encouraging your child to label length and width clearly.
- Practising multiplication facts to help with the area calculation.
- Using real-life examples like planning a garden or buying carpet.
Remember: It's okay if your child makes mistakes. These help them learn. Keep the tone positive and encouraging.
Practice questions
- What is the area of a rectangle that is 4 cm long and 2 cm wide?
- Find the area of a rectangle that is 6 m long and 3 m wide.
- Draw a rectangle on grid paper that is 5 squares long and 4 squares wide. What is its area?
- What is the area of a rectangle that is 7 cm long and 1 cm wide?
- Calculate the area of a rectangle that is 8 m long and 5 m wide.
Answers:
- Area = 4 cm × 2 cm = 8 cm²
- Area = 6 m × 3 m = 18 m²
- Area = 5 squares × 4 squares = 20 squares
- Area = 7 cm × 1 cm = 7 cm²
- Area = 8 m × 5 m = 40 m²
FAQ
What is area?
Area is the amount of space inside a shape. For rectangles, you find it by multiplying the length by the width.
How do I know which side is the length and which is the width?
The length is usually the longer side, and the width is the shorter side. If you're not sure, you can measure both and label them clearly.
Can I use grid paper to find area?
Yes! You can draw rectangles on grid paper and count the squares inside. This helps you check your multiplication.
Why do we write cm² or m²?
We write cm² or m² to show that we are talking about square units. This helps us understand that we are measuring area, not just length.
What if the rectangle is not a perfect shape?
For rectangles, we always use the formula length × width. If the shape is not a rectangle, we might need to use different methods to find the area.