Understanding ratios

Home learning focus

Today you will find out what ratios are, how ratios are written and how to convert between a ratio and a fraction.

This lesson includes:

  • one videos
  • three interactive activities

Learn

What is a ratio?

A ratio shows how much of one thing there is compared to another. Ratios are usually written in the form a:b.

If you are making orange squash and you mix one part orange to four parts water, then the ratio of orange to water will be 1:4 (1 to 4).

The order in which a ratio is stated is important. Changing the order of the numbers in a ratio changes the proportions and would mean the orange squash was very strong!

Ratio in a recipe

Watch this clip from BBC Teach on using ratio in a recipe

Ratios as fractions

Ratios can be used to show fractions and proportions of amounts. Proportion is used to show how quantities and amounts are related to each other.

Example

A room has to be painted blue and yellow in the ratio 2:3. Express the proportion of the room that has to be painted in each colour as a fraction.

There are five parts in this ratio: 2 blue + 3 yellow = 5 total

The fraction painted blue is ⅖ and the fraction painted yellow is ⅗.

Practise

Activity 1

Ratio quiz

Think you know about ratios? Prove it in this 10 question quiz.

Activity 2

Converting ratios and fractions

Now, see if you can complete this worksheet from White Rose Maths.

Ratios and fractions worksheet

Finished? Check your answers here.

Activity 3

Writing ratios as fractions

Keep practising! Here's another worksheet from Sparx to further your knowledge of ratios.

Year 8 - Writing Ratios as Fractions

Finished? Check your answers here.

There's more to learn

Have a look at these other resources around the BBC and the web.

KS3 Maths
BBC Bitesize Daily
Maths Challenge
audio
11-14 Maths
Women in mathematics
Science Museum games