A part to whole (sometimes part to part) comparison. If two things are proportional then the ratio of part to whole is maintained and the multiplicative relationship between parts is also maintained.

Checking and securing understanding of real world ratios

Maths

In the compound measures unit, pupils will be exploring the multiplicative relationship between different compound measures. Ratio will be one of the ways in which this is explored and the skills from this unit will aid understanding.

The ratio unit will cover comparing fractions, percentages and ratios and being able to move fluently between them. The percentages unit ensured pupils had the opportunity to work with finding the percentage of an amount and the opportunity to calculate interest.

Ratio

Select the units of measure that are metric.

A recipe for a stir-fry uses 30 ml of soy sauce. The recipe is for 4 people. How many millilitres of soy sauce would you need to make the recipe for 12 people?

A recipe for a stir-fry uses 36 ml of soy sauce. The recipe is for 6 people. How many millilitres of soy sauce would you need to make the recipe for 10 people?

A recipe for soup for 8 people uses 200 g of carrots. 
Andeep is making the soup for more people and has correctly scaled the recipe. He is using 375 g of carrots. 
How many people will this serve?

A scale on a map is 1 : 250 000.
How long would something that measured 3 cm on the map be in real life?

A scale on a map is 1 : 50 000.
How long would something that is 4 km in real life measure on the map?

There are only red and green sweets in a bag. If the ratio of red to green is 4 : 7, what fraction of the sweets in the bag are red?

There are only cars or bikes in a car park. If 40% are bikes, what is the ratio of cars : bikes?

There are only red, yellow and green marbles in a bag. $$\frac{1}{3}$$ are red, $$\frac{2}{5}$$ are yellow, write the ratio of red to yellow to green marbles.

A bag of sweets contains red, yellow and green sweets.
There are 250 sweets in the bag.
30% of them are red.
The rest are yellow and green in the ratio 3 : 4.
How many green sweets are there?

Laura and Sofia share some money in the ratio 2 : 7.
Laura gives $$\frac{3}{8}$$ of her money to Jacob.
If Jacob gets £33, how much does Sofia get?

Jacob, Andeep and Lucas receive some money.
Jacob gets $$\frac{2}{7}$$ of the money.
Andeep and Lucas share the rest in the ratio 4 : 7.
What proportion of the prize money does Andeep get?

This lesson will soon be taken down.

Checking and securing understanding of real world ratios

Lesson outcome