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Scratch Maths

Scratch random number blocks maths mission

A practical mini-mission using random number blocks to practise probability through questions, examples and child-friendly challenges.

Quick answer

You can use Scratch random number blocks to create fun maths challenges and learn about probability and chance. By making your Scratch project generate random numbers, you can explore how likely different outcomes are and practice your maths skills in a playful way.

Learning outcome

By the end of this page, you will be able to use Scratch random number blocks to create a simple maths game or challenge that generates random numbers and helps you learn about chance and probability. Success signs:
  • You can explain what a random number is
  • You can create a Scratch project that generates random numbers
  • You can use random numbers to play a maths game
  • You can predict how often certain numbers might come up

Why this matters

Random numbers are used in lots of fun things! In games, they decide who wins or what happens next. In science, they help researchers test ideas. In your daily life, random numbers help with things like choosing what to watch on TV or picking a restaurant. Learning how to use random numbers in Scratch helps you understand probability – that’s how likely something is to happen. This skill helps you think about chance and make better decisions in games, puzzles, and even real-life situations.

How it works

Using random numbers in Scratch is like rolling a dice or spinning a wheel. The computer picks a number for you without you choosing it. You can make Scratch pick a number between two values, like between 1 and 10, or between 10 and 20. This is done using the pick random block. When you use this block, you tell Scratch:
  1. What number to start from
  2. What number to end at
Then, every time your project runs, it will pick a new number between those two values. It’s like magic – but it’s actually maths!

Examples you can see

Let’s look at how to make a random number block work in Scratch. Example 1: Roll a dice You can make a dice that shows a random number between 1 and 6.
  • Use the pick random block
  • Set the start number to 1
  • Set the end number to 6
  • When the project runs, it will show a number between 1 and 6
Example 2: Choose a fruit Imagine you want to pick a random fruit from a basket.
  • Use the pick random block
  • Set the start number to 1
  • Set the end number to 5
  • Each time you run the project, it picks a different fruit
Here’s a table showing how this works for numbers 1 to 5:
Number Fruit
1 Apple
2 Banana
3 Orange
4 Grapes
5 Strawberry

Try it as a mini adventure

Adventure: The Mystery Box Challenge You are a detective who has found a mysterious box in the forest. Inside the box, there are 10 magic cards, each with a different number from 1 to 10. When you open the box, it will randomly pick one of the cards to give you a clue. You need to make a Scratch project that simulates this mystery box.
  1. Step 1: Open Scratch and create a new project
  2. Step 2: Add a sprite (like a box or a card)
  3. Step 3: Use the pick random block to pick a number between 1 and 10
  4. Step 4: Show the number on screen
  5. Step 5: Make the number change each time you click the green flag
Now, imagine that each number gives a different clue:
  • Number 1: "The treasure is hidden under the big tree"
  • Number 2: "The treasure is near the river"
  • Number 3: "The treasure is in the cave"
  • Number 4: "The treasure is under a rock"
  • Number 5: "The treasure is near the old bridge"
  • Number 6: "The treasure is in the garden"
  • Number 7: "The treasure is near the fire"
  • Number 8: "The treasure is under the hill"
  • Number 9: "The treasure is near the waterfall"
  • Number 10: "The treasure is in the cave"
Each time you run your project, it will give you a new clue to find the treasure!

Common mistakes

  • Mistake: Using the wrong numbers in the random block.
    Why it happens: Confusing the start and end numbers.
    Fix: Always double-check that the first number is smaller than the second number.
  • Mistake: Thinking that random numbers are predictable.
    Why it happens: Believing that if a number comes up once, it won’t come up again.
    Fix: Remember that random numbers can repeat – just like rolling a dice!
  • Mistake: Not using the green flag to start the random number.
    Why it happens: Not understanding how Scratch projects work.
    Fix: Click the green flag to start your project and see the random number.

Parent and carer guide

If you're helping your child with this Scratch mission, here’s how you can support them:
  • Encourage them to explain what a random number is in their own words
  • Ask them to predict what number they might get next
  • Try different ranges – like 1 to 20 or 5 to 15 – to see how it changes
  • Play the mystery box game together and see if they can guess the clues
  • Let them make their own version of the mystery box with their own clues
This is a great way to practice maths skills like number recognition, probability, and problem-solving. It also helps with creativity and logic. Don’t worry if they get confused at first – random numbers can be tricky to understand at first, but with practice, they’ll get the hang of it!

Practice questions

  1. What number will Scratch pick if you use the random block with start 1 and end 10?
  2. Can you make a random block that picks between 5 and 15? What are the start and end numbers?
  3. If you run your project 10 times, will you get the same number every time?
  4. How many different numbers can you get if you use a random block from 1 to 10?
  5. What would happen if you used a random block from 10 to 1?
Answers:
  1. Any number from 1 to 10
  2. Start = 5, End = 15
  3. No, because random numbers can repeat
  4. 10 different numbers (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
  5. Scratch will pick between 1 and 10, not 10 to 1

FAQ

What is a random number?

A random number is a number that is picked without you choosing it. It’s like rolling a dice – you don’t know what number will come up next.

Can I use random numbers in other games?

Yes! Many games use random numbers to make things fair and exciting. For example, dice games, card games, and even some video games use random numbers to decide what happens next.

Why is it useful to learn about random numbers?

Learning about random numbers helps you understand chance and probability. This is useful in games, science experiments, and even everyday decisions like choosing what to eat or what to do next.

Can I make more than one random number in Scratch?

Yes! You can use more than one random block in your project to generate multiple numbers at once. For example, you could roll two dice and add the numbers together.

How can I make my random number project more fun?

You can add sounds, costumes, or animations to your project. You can also create different messages or clues for each number that comes up. The more creative you are, the more fun your project will be!