X Tables
Maths Adventures

Bakery maths quest: perimeter

A story-led junior maths adventure using recipes, sharing and delicious fractions 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 shapes around your home or in your favourite places, like a bakery, garden, or playground. Success signs:
  • You can name the sides of a shape and add them up
  • You can measure shapes using a ruler or tape measure
  • You can work out how much fencing you need for a garden
  • You can solve a real-life problem using perimeter

Why this matters

Perimeter helps you figure out how much fencing you need for a garden, how far you walk around a playground, or how much ribbon you need to go around a cake. It's useful in real life, in games, and in your future maths adventures.

How it works

To find the perimeter of a shape, you add up the lengths of all its sides. Step-by-step:
  1. Look at the shape
  2. Find the length of each side
  3. Add all the lengths together
  4. Write your answer with the right unit (like metres or centimetres)

Examples you can see

Let's imagine you're helping in a bakery and need to build a safe zone around the dough mixing area. Example 1: Rectangle A rectangular dough mixing area is 5 metres long and 3 metres wide.
  • Two sides are 5 metres
  • Two sides are 3 metres
  • Perimeter = 5 + 5 + 3 + 3 = 16 metres
Example 2: Square A square baking tray has sides that are 4 centimetres long.
  • All four sides are 4 cm
  • Perimeter = 4 + 4 + 4 + 4 = 16 cm
Example 3: Triangle A triangular cake stand has sides of 6 cm, 6 cm, and 8 cm.
  • Perimeter = 6 + 6 + 8 = 20 cm

Try it as a mini adventure

Bakery Maths Quest: The Perimeter Challenge You are the head baker's assistant and need to build a safe zone around the new oven. The oven is shaped like a rectangle that is 2 metres long and 1 metre wide. You must find how much fencing you need to surround it. Step 1: What shape is the oven?
  • Rectangle
Step 2: What are the lengths of the sides?
  • Two sides are 2 metres
  • Two sides are 1 metre
Step 3: Add all the sides together.
  • Perimeter = 2 + 2 + 1 + 1 = 6 metres
Step 4: How much fencing do you need?
  • You need 6 metres of fencing
Mini challenge: Draw a shape with a perimeter of 10 units. What shape did you make?

Common mistakes

  • Mistake: Forgetting to add all the sides of a shape.
    Why it happens: It's easy to miss a side when counting.
    Fix: Use a pencil to point to each side as you add it up.
  • Mistake: Using the wrong unit of measurement.
    Why it happens: Confusing centimetres and metres.
    Fix: Always check if your shape is small (cm) or big (m).
  • Mistake: Thinking perimeter is the space inside the shape.
    Why it happens: Confusing perimeter with area.
    Fix: Remember: perimeter = around the edge. Area = inside the shape.

Parent and carer guide

To help your child with this, try these 5-10 minutes of fun:
  • Measure the perimeter of your dining table or bed using a tape measure or ruler
  • Ask them to find the perimeter of a book, a box, or a room
  • Play a game: "How many steps around the garden?"
  • Encourage them to draw shapes and calculate their perimeters
  • Ask them to explain how they found the perimeter
What to say:
  • "Let's measure the edge of this shape together"
  • "How many sides are there?"
  • "Can you count the units around the outside?"
What not to worry about:
  • They might make one mistake but that's part of learning
  • They might need to count twice to get the right answer
  • They might not know the word "perimeter" yet but they can still understand the idea

Practice questions

  1. What is the perimeter of a rectangle that is 6 cm long and 4 cm wide?
  2. What is the perimeter of a square with sides of 5 cm?
  3. What is the perimeter of a triangle with sides of 3 cm, 4 cm, and 5 cm?
  4. A garden is 10 m long and 5 m wide. What is the perimeter?
  5. What is the perimeter of a shape with sides 2 m, 2 m, 3 m, and 3 m?
Answers:
  1. 6 + 6 + 4 + 4 = 20 cm
  2. 5 + 5 + 5 + 5 = 20 cm
  3. 3 + 4 + 5 = 12 cm
  4. 10 + 10 + 5 + 5 = 30 m
  5. 2 + 2 + 3 + 3 = 10 m

FAQ

What is perimeter?

Perimeter is the total distance around the edge of a shape.

How do I find the perimeter of any shape?

Add up the lengths of all the sides of the shape.

Can I use a ruler to measure perimeter?

Yes, you can use a ruler or tape measure to find the length of each side, then add them up.

What's the difference between perimeter and area?

Perimeter is the distance around the edge of a shape. Area is the space inside the shape.

Why do we need to know perimeter?

Perimeter helps us work out how much fencing we need, how far we walk, or how much material we need for a border.