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Maths Adventures

Ocean maths quest: ratio

A story-led junior maths adventure using reefs, ships and underwater maps to mix recipes, scale drawings and compare quantities.

Quick answer

Ratios help us compare amounts or quantities, like how much of each ingredient you need to make a recipe, or how many fish are in different parts of a reef.

Learning outcome

By the end of this page, you will be able to compare amounts using ratios and understand how they help you share, measure, and plan things in real life – like mixing paint, making a treasure map, or planning a fish tank. Success signs:
  • You can say what a ratio means using words like "for every" or "out of"
  • You can match ratios to real-life situations like sharing snacks or mixing drinks
  • You can solve simple ratio problems using pictures or objects
  • You can describe how ratios help in games, cooking, or building

Why this matters

Ratios help you understand how things relate to each other. Whether you're mixing paint for a school art project, sharing a bag of sweets with friends, or planning how many fish to put in a tank, ratios help you make fair and smart decisions. In the ocean, ratios help divers know how much of each ingredient to add to their underwater mix, and how many fish live in each part of a reef.

How it works

A ratio shows how two or more amounts compare. You can write ratios in different ways:
  • With a colon: 3:2
  • With words: 3 to 2
  • As a fraction: 3/2
Think of ratios like a recipe. If a recipe says "for every 3 cups of flour, use 2 cups of sugar", that's a ratio of 3:2. Ratios help you make sure you have the right amount of each thing, no matter how much you're making.

Examples you can see

Let’s imagine you're on an Ocean Maths Quest! You're exploring a coral reef and find a treasure chest. Inside are 12 fish and 8 shells. How can you compare them? Step 1: Count how many of each thing.
  • Fish: 12
  • Shells: 8
Step 2: Write the ratio.
  • Fish to shells = 12:8
Step 3: Simplify the ratio.
  • 12:8 = 3:2 (because both 12 and 8 can be divided by 4)
So for every 3 fish, there are 2 shells. That's a ratio of 3:2. Let’s try another example: You're mixing a special underwater paint for your treasure map. The recipe says:
  • For every 4 drops of blue paint, use 2 drops of green paint
This is a ratio of 4:2, which simplifies to 2:1. So for every 2 drops of blue, you use 1 drop of green.

Try it as a mini adventure

Adventure: The Ocean Map Quest You are a young explorer who has found a map underwater. The map shows two parts of the ocean:
  • Part A: 15 fish and 10 seahorses
  • Part B: 9 fish and 6 seahorses
Your mission is to find the ratio of fish to seahorses in each part, and then decide which part has the same ratio. Step 1: Find the ratio for Part A.
  • Fish: 15
  • Seahorses: 10
  • Ratio = 15:10 = 3:2
Step 2: Find the ratio for Part B.
  • Fish: 9
  • Seahorses: 6
  • Ratio = 9:6 = 3:2
Step 3: Compare the ratios.
  • Both parts have the same ratio of 3:2
You’ve solved the map puzzle! Both parts of the ocean have the same number of fish for every seahorse.

Common mistakes

  • Mistake: Writing the ratio in the wrong order.
    • Why it happens: Confusing which number represents which item.
    • Fix: Always double-check that you're counting the right things. For example, if the question says "fish to shells", write fish first.
  • Mistake: Not simplifying the ratio.
    • Why it happens: Thinking that 12:8 is the same as 3:2 without checking.
    • Fix: Divide both numbers by their highest common factor (in this case, 4).
  • Mistake: Mixing up ratio with addition or subtraction.
    • Why it happens: Thinking that 3:2 means 3 + 2 = 5.
    • Fix: Remember ratios compare amounts, not add them together.

Parent and carer guide

Helping your child understand ratios can be fun and practical! Here’s how to support them in just 5–10 minutes:
  • Use everyday examples: When cooking, ask your child to help measure ingredients using ratios. For example, “If we need 2 cups of flour for every 1 cup of sugar, how much flour do we need if we use 4 cups of sugar?”
  • Play with ratios: Create a simple game using toys or snacks. For example, 3 red cars and 2 blue cars = 3:2 ratio.
  • Encourage drawing: Let your child draw pictures to show ratios. For example, draw 4 fish and 2 shells to show a 4:2 ratio.
  • Don’t pressure: Ratios are tricky at first. Be patient and keep making it fun!

Practice questions

  1. There are 6 dolphins and 4 whales. What is the ratio of dolphins to whales?
  2. There are 10 stars and 5 fish. What is the ratio of stars to fish?
  3. There are 12 turtles and 8 crabs. Simplify the ratio of turtles to crabs.
  4. There are 15 seahorses and 10 octopuses. What is the ratio of seahorses to octopuses?
  5. There are 8 seashells and 12 pearls. Simplify the ratio of seashells to pearls.
Answers:
  1. 6:4 = 3:2
  2. 10:5 = 2:1
  3. 12:8 = 3:2
  4. 15:10 = 3:2
  5. 8:12 = 2:3

FAQ

What is a ratio?

A ratio is a way to compare two or more amounts. It shows how much of one thing there is compared to another.

How do I simplify a ratio?

To simplify a ratio, divide both numbers by the biggest number that goes into both evenly. For example, 12:8 becomes 3:2 because 4 goes into both 12 and 8.

Can I use ratios with anything?

Yes! You can use ratios to compare anything – like the number of fish to shells, or the amount of paint to water.

Why do we use ratios in real life?

Ratios help us share things fairly, make recipes work, and plan things like how many fish to keep in a tank or how much paint to buy.

How can I make learning ratios more fun?

Try making ratios with toys, snacks, or even drawing pictures. You can also play games where you match ratios or find ratios in your environment!