Maths Adventures
Train maths quest: perimeter
A story-led junior maths adventure using timetables, distances and platform clues to measure fences, walls and safe zones around places.
Quick answer
Perimeter is the total distance around the edge of a shape. You can find it by adding up all the sides of a shape, like measuring how far you'd walk around a playground fence.Learning outcome
By the end of this page, you will be able to measure the perimeter of different shapes and solve problems about distances around objects, just like a train conductor planning safe routes. Success signs:- You can add up all the sides of a shape to find the perimeter
- You can measure objects around your home to find their perimeter
- You can solve simple problems about distances around fences, walls, or platforms
- You can explain how you found the perimeter to someone else
Why this matters
Perimeter is important for real-world tasks like planning how much fencing you need for a garden, how far a train travels around a station, or how much space you have to play with. It's also helpful for train conductors who need to know how far they've travelled or how much track they've covered. In games and building, you use perimeter to plan where to place things or how much material you need. It's a skill you use every day, even if you don't always notice!How it works
To find the perimeter of a shape, you simply add up all the sides around the outside. It's like walking around the edge of a shape and counting how far you go. Here's how to do it step by step:- Look at the shape and find all the sides
- Measure each side (or count the units if you're using a grid)
- Add all the side lengths together
- Write your answer with the correct units (like metres or centimetres)
Examples you can see
Let's imagine you're on a train journey and need to measure the safe zones around different platforms. Here are some examples: Example 1: Square platform A square platform has four sides that are all the same length. - Each side is 5 metres long - Perimeter = 5 + 5 + 5 + 5 = 20 metres Example 2: Rectangular platform A rectangular platform has two pairs of equal sides. - Length = 8 metres, Width = 4 metres - Perimeter = 8 + 4 + 8 + 4 = 24 metres Example 3: Triangle platform A triangular platform has three sides. - Side 1 = 6 metres, Side 2 = 6 metres, Side 3 = 6 metres - Perimeter = 6 + 6 + 6 = 18 metres Example 4: Irregular shape An unusual platform might have sides of different lengths. - Side 1 = 3 metres, Side 2 = 5 metres, Side 3 = 4 metres, Side 4 = 6 metres - Perimeter = 3 + 5 + 4 + 6 = 18 metresTry it as a mini adventure
Train Maths Quest: Measure the Safe Zone You are a young train conductor helping plan the safest routes for passengers. You need to measure different platform areas to make sure everyone has enough space to wait safely. Step 1: You find a square platform that is 7 metres on each side. What is the perimeter? Step 2: You need to check a rectangular platform that is 10 metres long and 5 metres wide. What is the perimeter? Step 3: You're looking at a triangular platform with sides of 4 metres, 4 metres, and 6 metres. What is the perimeter? Step 4: You find a strange platform with sides of 3 metres, 5 metres, 7 metres, and 4 metres. What is the perimeter? Step 5: You want to build a fence around the platform you measured in Step 4. How much fencing do you need?Common mistakes
- Mistake: Only adding two sides instead of all sides
Why it happens: Children might get confused by the shape and think they only need to measure the length and width
Fix: Always count all sides around the outside of the shape - Mistake: Forgetting to write units (metres, centimetres)
Why it happens: Kids might not notice that the answer should be in a measurement unit
Fix: Always add the correct unit at the end of your answer - Mistake: Counting the same side twice
Why it happens: When working with complex shapes, children might lose track of which sides they've already measured
Fix: Label each side clearly or draw a small mark on the shape to keep track
Parent and carer guide
To help your child with perimeter, you can:- Use everyday objects like books, boxes, or toys to measure and calculate perimeters
- Ask them to find the perimeter of their bedroom, garden, or playground
- Play a game where you measure different rooms and compare perimeters
- Encourage them to explain how they found the perimeter to you
- Use visual aids like drawing shapes or using grid paper to help them see all sides clearly
Practice questions
- What is the perimeter of a square with sides of 6 metres?
- What is the perimeter of a rectangle that is 9 metres long and 3 metres wide?
- What is the perimeter of a triangle with sides of 5 metres, 5 metres, and 8 metres?
- What is the perimeter of a shape with sides of 2 metres, 4 metres, 3 metres, and 5 metres?
- What is the perimeter of a square with sides of 10 metres?
- 6 + 6 + 6 + 6 = 24 metres
- 9 + 3 + 9 + 3 = 24 metres
- 5 + 5 + 8 = 18 metres
- 2 + 4 + 3 + 5 = 14 metres
- 10 + 10 + 10 + 10 = 40 metres
FAQ
What is perimeter?
Perimeter is the total distance around the outside edge of a shape. It's like walking all the way around a fence and measuring how far you've walked.
How do I find the perimeter of any shape?
Simply add up all the sides of the shape. No matter what shape it is, you just need to measure each side and add them together.
Can I find the perimeter of a circle?
Yes, but it's called the circumference instead of perimeter. For a circle, you use the formula: C = 2πr, where r is the radius.
Why do I need to know about perimeter?
Perimeter helps you plan how much material you need for fencing, how far you'll walk around a park, or how much space you have to play in. It's useful for many real-life situations!
What's the difference between perimeter and area?
Perimeter measures the distance around the outside of a shape, while area measures how much space is inside the shape. Think of perimeter as the fence around your garden and area as how much grass you have to play on.