Perimeter in real life

Quick answer

Perimeter is the total distance around the edge of a shape. You can find it by adding up all the sides. In real life, you use perimeter when measuring fences, frames, borders, and paths.

Learning outcome

By the end of this page, you will be able to measure the perimeter of shapes in real life and explain how it helps you solve everyday problems.

• You can add up all the sides of a shape to find its perimeter.
• You can measure the distance around objects like gardens, rooms, or playgrounds.
• You can use perimeter to work out how much fencing you need or how far you walk around a path.
• You can spot where perimeter is used in everyday life.

Why this matters

Perimeter helps you understand how much space something takes up around the outside. It's useful when you're planning to build something, like a fence for a garden or a frame for a picture. It helps you know how much material you need. In sports, you might measure how far you run around a track. In cooking, you might measure how much ribbon you need for a cake border. Perimeter is everywhere around us, and knowing how to find it helps you solve real problems.

How it works

Perimeter means "the distance around the edge of a shape". To find the perimeter:

1. Look at all the sides of the shape.
2. Measure each side.
3. Add up all the measurements.
4. The total is the perimeter.

For a rectangle, you add up the length and width, then double it. For a square, you multiply one side by 4. For a triangle, you add all three sides.

Examples you can see

Here are some ways you can see perimeter in real life:

Example 1: Garden Fence

You have a rectangular garden that is 6 metres long and 4 metres wide. To find the perimeter:

• Two sides are 6 metres long
• Two sides are 4 metres long
• Perimeter = 6 + 6 + 4 + 4 = 20 metres

You need 20 metres of fencing to go around the garden.

Example 2: Picture Frame

A picture frame is a square with each side 10 cm long. To find the perimeter:

• Perimeter = 10 + 10 + 10 + 10 = 40 cm

You need 40 cm of wood to make the frame.

Example 3: Playground Path

A playground is shaped like a pentagon (5 sides). The sides are 5 m, 6 m, 7 m, 6 m, and 5 m. To find the perimeter:

• Perimeter = 5 + 6 + 7 + 6 + 5 = 29 metres

You walk 29 metres around the edge of the playground.

Try it as a mini adventure

Adventure: Measure Your Home!

Imagine you're a detective trying to find out how much fencing you need for your garden. You have a small rectangular garden that is 5 metres long and 3 metres wide.

1. First, measure the length and width of your garden.
2. Draw a picture of your garden and label the sides.
3. Calculate the perimeter by adding all sides together.
4. Now, imagine you want to put a border of flowers around the garden. How far would that border go?

Use a tape measure or a ruler to help you. You can also use your feet to estimate the distance. Try to find the perimeter of other shapes in your house or garden too!

Common mistakes

• Mistake: Forgetting to measure all sides of a shape. Why it happens: Children might only measure a few sides or think one side is enough. Fix: Always check that you have measured every side of the shape.
• Mistake: Adding up the area instead of the perimeter. Why it happens: Some children mix up area and perimeter. Fix: Remember: perimeter is the distance around the edge, and area is the space inside.
• Mistake: Using the wrong units. Why it happens: Children might use centimetres when they should use metres. Fix: Always make sure you use the same unit for all measurements.

Parent and carer guide

Help your child understand perimeter by using everyday examples:

• Measure the edges of a table, book, or pillowcase.
• Ask them to walk around the edge of a room and count their steps to estimate the perimeter.
• Use a rope or string to trace the edge of a shape on the floor.
• Look for examples of perimeter in your home or garden, like the border of a rug or the frame of a picture.
• Encourage your child to draw shapes and label their sides to help them see how to add them up.

Don't worry if your child makes mistakes. They are part of the learning process. Ask questions like, "How did you figure that out?" or "What would happen if we changed one side?" This helps them think about their thinking.

Practice questions

1. What is the perimeter of a square with sides of 7 cm?
2. A rectangular garden is 10 metres long and 5 metres wide. What is its perimeter?
3. A triangle has sides of 3 m, 4 m, and 5 m. What is its perimeter?
4. You want to put a fence around a rectangular field that is 8 m long and 6 m wide. How much fence do you need?
5. A hexagon has sides of 4 cm each. What is its perimeter?

Answers:

1. 28 cm
2. 30 metres
3. 12 metres
4. 28 metres
5. 24 cm

FAQ

What is perimeter?

Perimeter is the total distance around the edge of a shape. You can find it by adding up all the sides of the shape.

How do I measure perimeter?

Measure each side of the shape, then add all the measurements together. For rectangles, you can double the sum of length and width.

Why do we need to know perimeter?

Perimeter helps us figure out how much material we need for things like fences, borders, or paths. It also helps us understand how far we walk or run around a shape.

Can all shapes have a perimeter?

Yes! Any shape that has sides (like squares, rectangles, triangles, or circles) can have a perimeter. For circles, we call it the circumference, but it’s still the distance around the edge.

How is perimeter different from area?

Perimeter is the distance around the edge of a shape, while area is the space inside the shape. For example, a square with sides of 5 cm has a perimeter of 20 cm but an area of 25 square cm.