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Maths Adventures

Alien planet maths quest: subtraction

A story-led junior maths adventure using strange number systems and gravity jumps to work out what is left after trades, rescues or escapes.

Quick answer

Subtraction is about taking away or finding what is left. In this alien maths quest, you'll use subtraction to work out how many items are left after trading, rescuing, or escaping from strange alien places.

Learning outcome

By the end of this page, you will be able to use subtraction to find what is left when you take away or remove items, and you will understand how subtraction helps you solve problems in alien space adventures. Success signs:
  • You can count backwards or take away objects to find the answer
  • You can use subtraction to solve problems about space rescues, trades, or escapes
  • You can show subtraction using pictures, number lines, or real objects
  • You can explain how subtraction helps you solve space puzzles

Why this matters

Subtraction is a superpower in space! When you're on an alien planet, you might need to know how many energy crystals are left after sharing them with your spaceship crew. Or how many space creatures you've rescued from a strange cave. Subtraction helps you figure out how many things are left after some are taken away or used up. It's also important in games, sports, and everyday life when you want to know how much is left after using or sharing.

How it works

Subtraction is like taking away or removing things from a group. When you subtract, you start with a number and take away some of it. The answer is what is left. For example, if you have 10 space apples and you eat 3, you can count backwards or take 3 apples away to see how many are left. Here are the simple steps:
  1. Start with a group of things (a number)
  2. Take away some of the things (subtract)
  3. Count or calculate how many are left

Examples you can see

Let's imagine you're on a space mission to Planet Zog. You start with 12 energy crystals and you give 5 to your alien friend. How many do you have left? Method 1: Counting backwards Start at 12, count backwards 5 times: 12, 11, 10, 9, 8, 7 You have 7 crystals left. Method 2: Taking away objects If you have 12 blocks and take away 5 blocks, you can count the 7 blocks that are left. Method 3: Using a number line Start at 12, move back 5 spaces: 12 → 11 → 10 → 9 → 8 → 7 You have 7 left.

Try it as a mini adventure

Alien Rescue Mission You are a space explorer on Planet Zog. You have 15 space creatures to rescue from a cave. You have already rescued 8 of them. How many more do you need to rescue? Step-by-step challenge: 1st time: You start with 15 creatures 2nd time: You rescue 8 creatures 3rd time: You need to find how many are left 4th time: Count backwards from 15: 15, 14, 13, 12, 11, 10, 9, 8 5th time: You have 7 creatures left to rescue Mini adventure: Draw a picture of your spaceship with 15 space creatures. Cross out 8 of them. How many are left? Try this with 10 space creatures and take away 3. How many are left?

Common mistakes

  • Mistake: Thinking that 10 - 3 = 13 instead of 7
    Why it happens: Confusing addition with subtraction
    Fix: Use counting backwards or take away objects to check your answer
  • Mistake: Forgetting to start with the bigger number
    Why it happens: Not understanding that subtraction means taking away
    Fix: Always start with the larger number and count backwards
  • Mistake: Counting forwards instead of backwards
    Why it happens: Not understanding that subtraction means removing
    Fix: Practice counting backwards from larger numbers

Parent and carer guide

Help your child by:
  • Using real objects like toys or snacks to show subtraction
  • Practising counting backwards from 10 to 1
  • Encouraging them to explain how they solved a subtraction problem
  • Using everyday situations like sharing snacks or counting down to bedtime
  • Noticing when they get confused and gently reminding them to count backwards or use objects
Five-minute activity: Set out 10 small toys. Ask your child to take away 4 toys. Then ask "How many are left?" Encourage them to count backwards or physically remove the toys to find the answer.

Practice questions

  1. There are 12 space apples. You eat 5. How many are left? Answer: 7
  2. You have 15 energy crystals. You give 6 to your friend. How many do you have now? Answer: 9
  3. There are 10 space creatures in a cave. 4 escape. How many are left? Answer: 6
  4. You start with 13 stars. You lose 7. How many stars do you have left? Answer: 6
  5. There are 14 alien eggs. 9 hatch. How many eggs are left? Answer: 5

FAQ

What is subtraction?

Subtraction is when you take away or remove some of something. It helps you find out how much is left.

How do I know when to use subtraction?

You use subtraction when something is taken away or used up. For example, if you have 10 cookies and eat 3, you use subtraction to find how many are left.

Can I use subtraction with big numbers?

Yes! You can subtract any numbers. Even numbers like 100 or 1000. Just remember to count backwards or take away the correct amount.

How can I practice subtraction at home?

You can practice by counting backwards, using toys or snacks, or solving simple space-themed problems like "I had 8 stars, I gave 3 away, how many are left?"

Why do we need to learn subtraction?

Subtraction helps you solve problems in space adventures, at home, and in games. It helps you know how much is left after using or sharing things.