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Maths Adventures

Museum maths quest: perimeter

A story-led junior maths adventure using artefacts, clues and history puzzles to measure fences, walls and safe zones around places.

Quick answer

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

Learning outcome

By the end of this page, you will be able to measure the perimeter of any shape by adding up all its sides, and you will understand how to use this skill to solve puzzles and plan safe zones in museums. Success signs:
  • You can find the perimeter of a rectangle by adding up all four sides
  • You can measure the distance around a shape using a ruler or measuring tape
  • You can solve a simple puzzle that involves finding the perimeter of a museum room
  • You can explain why perimeter is useful when planning safe areas for visitors

Why this matters

Perimeter helps you know how much space is around something. In a museum, knowing the perimeter helps you plan where to put signs, how much fencing you need, or where to set up safe zones for children. It's also useful when you're designing a garden, building a fence, or even planning a football pitch. Perimeter is one of the most practical maths skills you'll use in everyday life.

How it works

To find the perimeter of any shape, you simply add up all the sides. Here's how to do it step by step:
  1. Look at the shape and count how many sides it has
  2. Measure each side using a ruler or measuring tape
  3. Add all the measurements together
  4. The total is the perimeter
For a rectangle, you can also use a shortcut:
  • Measure the length (long side)
  • Measure the width (short side)
  • Add the length and width together
  • Multiply that total by 2

Examples you can see

Let's imagine you are on a Museum Maths Quest and you find a clue that says: "The perimeter of the ancient Egyptian display case is 20 metres. If the case is a rectangle and one side is 6 metres, what is the length of the other side?" Here's how to solve it:
  1. Rectangle has 4 sides
  2. Two sides are 6 metres each (the long sides)
  3. Two sides are unknown (the short sides)
  4. Perimeter = 20 metres
  5. 2 × 6 = 12 metres
  6. 20 - 12 = 8 metres
  7. 8 ÷ 2 = 4 metres
  8. So the other two sides are 4 metres each
Another example: You are planning a safe zone around a dinosaur exhibit. The exhibit is a square with sides of 5 metres. What is the perimeter?
  • 4 sides
  • Each side is 5 metres
  • Perimeter = 5 + 5 + 5 + 5 = 20 metres
Here's a real-world example: A museum guard needs to place rope around a rectangular art display that is 8 metres long and 4 metres wide. How much rope does the guard need?
  • Length = 8 metres
  • Width = 4 metres
  • Perimeter = 2 × (8 + 4) = 2 × 12 = 24 metres

Try it as a mini adventure

Museum Maths Quest: The Lost Treasure Room You are on a treasure hunt in the museum! You found a clue that says: "To open the secret treasure room, you must find the perimeter of the room that is shaped like a rectangle. The room is 10 metres long and 6 metres wide. What is the perimeter?" Here's your adventure:
  1. First, you need to measure the room
  2. Find the length: 10 metres
  3. Find the width: 6 metres
  4. Count the sides: 4 sides
  5. Calculate: 2 × (10 + 6) = 2 × 16 = 32 metres
  6. Write down the answer: 32 metres
Now you can unlock the treasure room! You also need to make sure there's enough space for visitors. If you want to put a safety barrier around the room, you'll need 32 metres of rope.

Common mistakes

  • Mistake: Forgetting to measure all sides
    Why it happens: Kids get excited and miss one side when counting
    Fix: Use a finger to trace around the shape and count each side as you go
  • Mistake: Adding the length and width together without doubling
    Why it happens: Confusing perimeter with area
    Fix: Remember: Perimeter = 2 × (length + width)
  • Mistake: Using the wrong unit of measurement
    Why it happens: Mixing up metres and centimetres
    Fix: Always check that all measurements are in the same unit before adding

Parent and carer guide

You can help your child by:
  • Playing a perimeter game at home using a rectangular book, table, or room
  • Measuring the perimeter of different objects together
  • Using everyday items like floor tiles or garden fencing to show how perimeter works
  • Encouraging your child to explain how they found the perimeter
  • Practising with different shapes and sizes to build confidence
This is a fun way to show your child how maths is used in real life. Don't worry if they make mistakes – that's how we learn! Remember to praise their effort, not just the correct answer.

Practice questions

  1. What is the perimeter of a rectangle that is 5 metres long and 3 metres wide?
  2. A square has sides of 7 metres. What is its perimeter?
  3. Find the perimeter of a rectangle with sides of 12 metres and 8 metres.
  4. A museum display case is 4 metres long and 2 metres wide. What is its perimeter?
  5. What is the perimeter of a square with sides of 10 metres?
Answers:
  1. 2 × (5 + 3) = 2 × 8 = 16 metres
  2. 4 × 7 = 28 metres
  3. 2 × (12 + 8) = 2 × 20 = 40 metres
  4. 2 × (4 + 2) = 2 × 6 = 12 metres
  5. 4 × 10 = 40 metres

FAQ

What is perimeter?

Perimeter is the total distance around the edge of a shape. It's like walking all the way around a shape and seeing how far you've walked.

How do I find the perimeter of a rectangle?

Measure the length and width, then add them together and multiply by 2. For example, a rectangle with length 6 metres and width 4 metres has a perimeter of 2 × (6 + 4) = 20 metres.

Can I find the perimeter of any shape?

Yes! You can find the perimeter of any shape by adding up all the sides. This works for triangles, squares, rectangles, and even irregular shapes.

Why do I need to know perimeter?

Perimeter is useful for many real-life situations like planning a garden, putting up a fence, setting up a safe zone in a museum, or even for sports fields. It helps you know how much space you need around something.

What's the difference between perimeter and area?

Perimeter is the distance around the outside of a shape, while area is the amount of space inside the shape. For example, a rectangle might have a perimeter of 12 metres but an area of 8 square metres.