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Maths Without Realising

You use maths when comparing heights

A short, exciting page showing children how comparing heights already uses measurement.

Quick answer

You use maths when comparing heights by measuring, ordering, and understanding how much taller or shorter something is.

Learning outcome

By the end of this page, you will understand how comparing heights uses measurement and numbers to tell you how much taller or shorter things are. Success signs:
  • You can measure two things and say which one is taller
  • You can find out how much taller one thing is than another
  • You can use words like "taller", "shorter", "the same height", and "how much taller"
  • You can compare your height to a friend or family member

Why this matters

Comparing heights helps you understand the world around you. It's useful when you're choosing the right chair for your height, stacking books, building with blocks, or playing games where you need to know who's tallest or shortest. It's also important for science, sports, and even for understanding how you grow over time. You're already doing maths when you look at a tower of building blocks and think, "That tower is taller than mine!"

How it works

When you compare heights, you are doing maths by:
  1. Measuring how tall something is
  2. Looking at the numbers to see which is bigger or smaller
  3. Using words like "taller", "shorter", or "the same height"
  4. Working out how much taller or shorter something is
You can compare heights using:
  • Objects you can see and touch
  • Measuring tools like rulers or metre sticks
  • Numbers and counting
  • Simple subtraction to find the difference

Examples you can see

Let's look at some fun examples of comparing heights: Example 1: Your bedroom Imagine you are 110 cm tall and your bed is 30 cm high. You can compare the two by saying:
  • Your bed is 30 cm high
  • You are 110 cm tall
  • You are 80 cm taller than your bed (because 110 - 30 = 80)
Example 2: Building blocks You have a tower that is 8 blocks high. Your friend's tower is 12 blocks high.
  • Your tower: 8 blocks
  • Friend's tower: 12 blocks
  • Friend's tower is 4 blocks taller (because 12 - 8 = 4)
Example 3: Plants in the garden You have a sunflower that is 75 cm tall and a tomato plant that is 50 cm tall.
  • Sunflower: 75 cm
  • Tomato plant: 50 cm
  • Sunflower is 25 cm taller (because 75 - 50 = 25)

Try it as a mini adventure

Adventure: The Great Height Hunt You are going on a treasure hunt in your house. Your mission is to find 3 different things and compare their heights. 1st time: Find a book and measure it. It is 20 cm tall. 2nd time: Find a pencil case and measure it. It is 15 cm tall. 3rd time: Find a toy car and measure it. It is 8 cm tall. Now, answer these questions:
  • Which is the tallest object?
  • Which is the shortest object?
  • How much taller is the book than the pencil case?
  • How much taller is the book than the toy car?
Challenge: Draw a picture of your three objects and write the height of each one. Then, write how much taller one is than another.

Common mistakes

  • Mistake: Thinking that the bigger number means the object is shorter.
    • Why it happens: Confusing the numbers when comparing
    • Fix: Remember that if one thing is 10 cm tall and another is 5 cm tall, the 10 cm one is taller.
  • Mistake: Not using the same units when comparing.
    • Why it happens: Mixing up cm and mm or forgetting to measure in the same way
    • Fix: Always measure everything in the same unit, like centimetres.
  • Mistake: Forgetting to subtract to find the difference.
    • Why it happens: Only comparing the numbers without working out how much taller
    • Fix: After comparing, subtract the smaller number from the bigger one to find the difference.

Parent and carer guide

Parents and carers can help by:
  • Letting children measure different things around the house
  • Using words like "taller", "shorter", and "how much taller" in everyday conversations
  • Encouraging children to compare their own height to others
  • Using real-life examples like comparing how tall you are to your pet or a chair
  • Playing simple games where children guess who is taller or shorter before measuring
Five-minute help tips:
  1. Ask your child to find two toys and compare their heights
  2. Measure your child's height and compare it to a door or wall
  3. Use a ruler to measure different books and order them from shortest to tallest
  4. Play a game where you say "Who is taller?" and let them guess before measuring
  5. Draw a chart showing how tall different family members are

Practice questions

  1. Tom is 120 cm tall. His sister is 90 cm tall. How much taller is Tom?
  2. A tree is 400 cm tall. A flower is 20 cm tall. How much taller is the tree?
  3. Emma is 105 cm tall. Her brother is 115 cm tall. How much taller is her brother?
  4. A dog is 60 cm tall. A cat is 35 cm tall. How much taller is the dog?
  5. Sam is 130 cm tall. His dad is 170 cm tall. How much taller is his dad?
Answers:
  1. Tom is 30 cm taller (120 - 90 = 30)
  2. The tree is 380 cm taller (400 - 20 = 380)
  3. Her brother is 10 cm taller (115 - 105 = 10)
  4. The dog is 25 cm taller (60 - 35 = 25)
  5. His dad is 40 cm taller (170 - 130 = 40)

FAQ

What does it mean to compare heights?

Comparing heights means looking at two or more things and deciding which one is taller or shorter, or how much taller or shorter one is than another.

Why is comparing heights useful?

It helps you choose the right chair, stack things safely, understand how you grow, and play games where height matters.

How can I practice comparing heights at home?

You can measure different objects like books, toys, or family members and compare their heights using words like "taller" and "shorter".

Can I use maths to compare heights without measuring?

Yes, you can guess which is taller and then measure to check. This helps you get better at estimating.

What if I don't have a ruler?

You can use your hands, feet, or a stick to measure and compare. You can also compare by looking at things side by side.