Scratch sprite scaling maths mission

Quick answer

When you scale a Scratch sprite, you change its size by making it bigger or smaller using a scale factor. You can use multiplication to work out how big or small the sprite should be after scaling.

Learning outcome

By the end of this page, you will be able to use multiplication to find the new size of a sprite when you scale it up or down in Scratch.

• You can explain what happens to a sprite when you change its scale
• You can multiply a sprite’s size by a scale factor to find its new size
• You can solve problems about sprite scaling using simple multiplication
• You can check if your scaled sprite looks right in a Scratch project

Why this matters

Scaling sprites in Scratch helps you make your projects look more fun and realistic. Whether you're making a game with big monsters or tiny characters, you need to know how to change their size. This maths helps you build better projects, just like how builders use maths to make sure their houses are the right size.

Learning about scaling also helps you understand bigger maths ideas like proportions, ratios, and how things grow or shrink in real life. You use this maths when you’re baking a cake and need to double the recipe, or when you're drawing a map and need to make things smaller or bigger to fit on the paper.

How it works

Scaling a sprite means changing how big or small it looks. In Scratch, you can change the size of a sprite by using a scale factor. A scale factor is a number that tells you how much to multiply the sprite's size by.

Here's how it works step-by-step:

1. Start with the sprite’s original size (usually 100%)
2. Decide how much you want to change the size (the scale factor)
3. Multiply the original size by the scale factor
4. Use the result to set the new size of the sprite

For example, if a sprite is 100% and you want to make it 2 times bigger, you multiply 100% by 2. The new size is 200%.

Examples you can see

Let’s look at some examples of scaling sprites in Scratch. These are things you can imagine or even try in a Scratch project!

Example 1: Making a sprite bigger

Imagine your sprite is 100% big. You want to make it 3 times bigger. What do you do?

You multiply: 100% × 3 = 300%

So the sprite becomes 300% big!

Example 2: Making a sprite smaller

Your sprite is 100% big. You want to make it half the size. What do you do?

You multiply: 100% × 0.5 = 50%

So the sprite becomes 50% big!

Example 3: Scaling by 1.5

Your sprite is 100% big. You want to make it 1.5 times bigger. What do you do?

You multiply: 100% × 1.5 = 150%

So the sprite becomes 150% big!

Real-world example: Scaling in a recipe

Imagine you are making a pizza. The recipe says to use 100g of cheese. But you want to make the pizza bigger, so you need 3 times more cheese. How much cheese do you need?

You multiply: 100g × 3 = 300g

So you need 300g of cheese!

Try it as a mini adventure

Let’s go on a Scratch Sprite Scaling Mission!

You are a space explorer and you’ve discovered a new planet. On this planet, everything is either bigger or smaller than on Earth. You need to create a spaceship that can change size to fit different spaces on the planet.

Here’s your mission:

1. Your spaceship is 100% big
2. You find a tiny cave that only fits a 20% sized spaceship
3. You find a giant cave that fits a 500% sized spaceship
4. You find a medium cave that fits a 150% sized spaceship

Now, help your spaceship change size for each cave. What scale factor do you use?

Try this in Scratch:

1. Start with your spaceship at 100% size
2. Use the change size to block
3. Try scaling to 20%, 500%, and 150%
4. Notice how the spaceship looks different each time

Can you make a sprite that changes size in a cool way? Maybe it starts small, grows to big, and then shrinks again!

Common mistakes

• Mistake: Forgetting to multiply by the scale factor
• Why it happens: Children might just type in the scale factor without using multiplication
• Fix: Always multiply the original size by the scale factor

• Mistake: Using a scale factor of 0
• Why it happens: Children might think scaling by 0 makes a sprite disappear, which is true, but they might not know why
• Fix: Explain that scaling by 0 makes the sprite invisible, not that it’s a mistake

• Mistake: Thinking that 100% is the biggest size
• Why it happens: Children might think 100% is the only size, not knowing it can be scaled up or down
• Fix: Show that 100% can be 100% or 200% or 50%

Parent and carer guide

As a parent or carer, you can help your child with sprite scaling by:

1. Playing with Scratch together and trying different scale factors
2. Using everyday examples like cooking or building to show scaling
3. Encouraging your child to explain how scaling works in their project
4. Checking that they multiply correctly, not just type in the number
5. Letting them make mistakes and figure out why they happened

Remember: Scaling is a fun way to learn multiplication and proportions. Don’t worry if your child makes a mistake – it’s part of learning!

Practice questions

Try these questions to see how well you understand sprite scaling:

1. If a sprite is 100% and you scale it by 2, what is the new size?
2. If a sprite is 100% and you scale it by 0.5, what is the new size?
3. If a sprite is 100% and you scale it by 3, what is the new size?
4. If a sprite is 100% and you scale it by 1.2, what is the new size?
5. If a sprite is 100% and you scale it by 0.25, what is the new size?

Answers:

1. 100% × 2 = 200%
2. 100% × 0.5 = 50%
3. 100% × 3 = 300%
4. 100% × 1.2 = 120%
5. 100% × 0.25 = 25%

FAQ

What is sprite scaling in Scratch?

Sprite scaling in Scratch means changing the size of a character or object by making it bigger or smaller using a scale factor.

How do I scale a sprite in Scratch?

You use the "change size to" block and multiply the original size by a scale factor to get the new size.

Can I scale a sprite to 0%?

Yes, but it will make the sprite invisible, not disappear completely.

Why do we use scaling in games?

Scaling helps make games more interesting and realistic. It lets you have different-sized characters, items, or environments.

How can I practice scaling at home?

You can use real objects like LEGO blocks or toys and change their sizes to practice scaling. You can also draw and then make them bigger or smaller.