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Maths Adventures

Knight maths quest: perimeter

A story-led junior maths adventure using quests, shields and tournament scores to measure fences, walls and safe zones around places.

Quick answer

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

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. Success signs:
  • You can count the sides of a shape and add them up
  • You can measure a shape in metres or centimetres
  • You can find the perimeter of rectangles, squares, and other shapes
  • You can help a knight build a fence around a safe zone

Why this matters

Perimeter helps you know how much fencing you need for a garden, how far you run around a playground, or how much space a knight needs to build a safe zone. It's like measuring the edge of a shape, which is useful in games, building, sports, and daily life.

How it works

To find the perimeter of any shape:
  1. Look at all the sides of the shape
  2. Measure each side (in centimetres or metres)
  3. Add all the side lengths together
  4. The total is the perimeter

Examples you can see

Let's imagine you are a knight in a quest. You need to build a fence around your safe zone. You have a square safe zone that is 5 metres on each side. How much fencing do you need? You have a square with 4 sides, each 5 metres long. 5 + 5 + 5 + 5 = 20 metres So you need 20 metres of fencing. Another example: A rectangular garden has a length of 8 metres and a width of 4 metres. The garden has 2 sides that are 8 metres and 2 sides that are 4 metres. 8 + 8 + 4 + 4 = 24 metres So the perimeter is 24 metres. Try this: Draw a shape with 5 sides. Measure each side and add them up to find the perimeter.

Try it as a mini adventure

Knight's Quest: Build the Safe Zone You are a brave knight on a quest to build a safe zone for your kingdom. The safe zone must be a rectangle that is 6 metres long and 3 metres wide.
  1. First, draw your rectangle on paper
  2. Measure each side: 6m, 3m, 6m, 3m
  3. Add all the sides together: 6 + 3 + 6 + 3 = ?
  4. How many metres of fence do you need?
4th time: You need to build a square safe zone that is 4 metres on each side. 5th time: What is the perimeter of your square? 6th time: You find a treasure map that shows a triangular safe zone. Each side is 5 metres. What is the perimeter?

Common mistakes

  • Mistake: Forgetting to measure all sides of a shape
    Why it happens: The knight gets distracted by shiny treasure and forgets to count all the sides
    Fix: Use a ruler or measuring tape to check each side carefully
  • Mistake: Adding up the area instead of the perimeter
    Why it happens: The knight thinks "how much space is inside" instead of "how far around the edge"
    Fix: Remember: perimeter = distance around the edge, area = space inside
  • Mistake: Not using the same units (metres and centimetres mixed)
    Why it happens: The knight measures one side in centimetres and another in metres
    Fix: Always measure everything in the same unit (like all centimetres or all metres)

Parent and carer guide

You can help your child learn perimeter by:
  • Looking at shapes in everyday life, like a book cover or a window
  • Measuring the edges of objects together
  • Using a ruler or tape measure to find each side
  • Adding the measurements together
  • Practising with simple shapes like squares and rectangles
Remember: It's okay if your child makes mistakes. They're learning! Encourage them to check their work and ask questions.

Practice questions

  1. What is the perimeter of a square with sides of 7 metres?
  2. A rectangle has sides of 10 metres and 5 metres. What is its perimeter?
  3. What is the perimeter of a triangle with sides of 6 metres each?
  4. A garden is 8 metres long and 4 metres wide. What is its perimeter?
  5. How much fencing do you need for a square safe zone that is 9 metres on each side?
Answers:
  1. 28 metres
  2. 30 metres
  3. 18 metres
  4. 24 metres
  5. 36 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 measuring how far you walked.

How do I find the perimeter of a square?

Since all four sides of a square are the same length, you can multiply one side by 4. For example, if one side is 5 metres, the perimeter is 5 × 4 = 20 metres.

Can I measure perimeter in centimetres?

Yes! You can measure perimeter in any unit you like, like centimetres, metres, or even inches. Just make sure you use the same unit for all sides.

Why do knights need to know perimeter?

Knights need to know perimeter to build fences, plan safe zones, and measure how much space they need for their adventures. It's like planning where to put a wall around a garden!

What if a shape has more than 4 sides?

It works the same way! Just add up all the sides. For example, a pentagon has 5 sides, so you add 5 sides together to find the perimeter.