Ratio KS2 — A Year 6 Guide to Ratio & Proportion

What Is a Ratio?

A ratio is just a way of comparing two (or more) amounts. “For every 2 red sweets, there are 3 blue sweets” gives us the ratio 2:3. That’s it. No percentages, no decimals — just a comparison.

Your child already uses ratios without realising. Squash instructions say “1 part cordial to 4 parts water” — that’s a ratio of 1:4. Paint mixing, cake recipes, even sharing out crisps at a party — ratios are everywhere once you start looking.

Sharing in a Ratio

This is the classic SATs question. “Share £20 between Sam and Jo in the ratio 3:2.” Here’s how to walk through it:

1. Add the ratio parts together: 3 + 2 = 5 parts.
2. Divide the total by the number of parts: £20 ÷ 5 = £4 per part.
3. Give each person their share: Sam gets 3 × £4 = £12. Jo gets 2 × £4 = £8.

Quick check: £12 + £8 = £20. It adds up, so you know it’s right. Encourage your child to always do this final check — it catches mistakes before they cost marks.

Scaling Up and Down

“A recipe for 4 people uses 200g of flour. How much flour for 6 people?” This is proportion — scaling quantities by the same factor. The trick is to find the amount for one person first.

200g ÷ 4 = 50g per person. Then 50g × 6 = 300g. Done. Most children find this type straightforward once they see the “find the value of one” step.

Trickier versions might say “for 10 people” or use amounts that don’t divide neatly. The method stays the same — find one, then multiply.

Ratio vs Fraction

SATs questions sometimes ask children to switch between ratio and fraction notation, and this is where things get muddled. In our earlier example, the ratio is 3:2. The total number of parts is 5. So Sam’s fraction is 3/5 and Jo’s is 2/5.

The key thing to remember: the denominator of the fraction is the total of the ratio parts, not one of the numbers in the ratio. Children often write 3/2 instead of 3/5 — just remind them to add the parts first.

Ratio in SATs Reasoning Papers

Ratio and proportion typically appear on reasoning Paper 2 or Paper 3 as a word problem worth 1–2 marks. The question might be about sharing sweets, mixing paint, or scaling a recipe. Sometimes it’s dressed up with “for every X there are Y” wording.

The maths is rarely harder than dividing and multiplying. What earns the marks is setting up the problem properly — finding the total parts, finding the value of one part, and showing the working clearly.

Common Mistakes

• Forgetting to find the total number of parts before dividing.
• Mixing up which person gets which share — always label your working.
• Not simplifying ratios when asked. 6:4 should be written as 3:2.
• Confusing ratio with difference. “3:2” doesn’t mean “one more”.

How to Practise at Home

The best ratio practice doesn’t feel like schoolwork. Cook together and double a recipe — “if we need 150g for 4, how much for 8?” Share out snacks unevenly on purpose: “3 for you, 2 for your brother — what’s the ratio?” Make squash and talk about the cordial-to-water ratio.

Once the idea makes sense in real life, the SATs-style questions become much less intimidating. The penny drops faster when they can picture the sweets on the table.