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Lesson 3 of 10

Explain how to represent ratio and to calculate unknown values

You can explain how to use representations to calculate unknown values.

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View unit
Lesson 3 of 10
New
New

Explain how to represent ratio and to calculate unknown values

You can explain how to use representations to calculate unknown values.

Download all

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Lesson details

Key learning points

  1. Bar models can represent unequal sharing or many to many sharing with three variables.
  2. Representations show the relationship between the three variables.
  3. The representation helps to identify the calculations needed to solve the problem.

Keywords

  • Variable - A variable is a value which can be represented by more than one number within a situation or equation

Common misconception

Relating the elements of the multiplication and equation to the values in the bar models.

Ensure that pupils can explain what the values in the equation represent and where they are in the bar models.

Emphasise the use of the language "for every" to secure the understanding of ratio and encourage pupils to explain and compare the representations used
Teacher tip

Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Prior knowledge starter quiz

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6 Questions

Q1.
What is 3 times more than 4?

Correct answer: 12
7
9
14

Q2.
How many 7s are there in 28?

21
3
Correct answer: 4
5

Q3.
Which of these numbers are multiples of 6?

3
Correct answer: 6
9
Correct answer: 12
Correct answer: 24

Q4.
A recipe uses 2 eggs for every 5 spoons of flour. If you use 12 eggs, how many spoons of flour will you need?

Correct Answer: 30 spoons of flour, You'll need 30, $$5 \times 6 = 30$$

Q5.
A recipe uses 2 eggs for every 5 spoons of flour. If you use 25 spoons of flour, how many eggs will you need?

Correct Answer: You will need 10 eggs, $$2 \times 5 = 10$$

Q6.
A recipe uses 2 eggs for every 5 spoons of flour. If you use 1 egg, how many spoons of flour will you need?

You can't make the recipe with 1 egg
2 spoons of flour
3 spoons of flour
4 spoons of flour
Correct answer: 2 and a half spoons of flour

Assessment exit quiz

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6 Questions

Q1.
Each quiz team is made up of 3 adults and 2 children. If there are 8 children taking part, how many teams are there?

2
3
Correct answer: 4
5
6

Q2.
Each quiz team is made up of 3 adults and 2 children. If there are 15 adults taking part, how many teams are there?

2
3
4
Correct answer: 5
6

Q3.
Each quiz team is made up of 3 adults and 2 children. If there are 7 teams, how many adults are taking part?

Correct Answer: There are 21 adults, $$3 \times 7 = 21$$

Q4.
Each quiz team is made up of 3 adults and 2 children. If there are 25 people taking part, which equation represents how many of them are children?

Correct answer: $$2 \times 5 = 10$$
$$2 \times 3 = 6$$
$$3 \times 5 = 15$$
$$25 \div 2 = 12.5$$

Q5.
Each quiz team is made up of 3 adults and 2 children. Which bar model accurately represents 6 quiz teams?

Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz

Q6.
How many variables are there in the quiz team made up of 3 children and 2 adults?

1
2
Correct answer: 3
4
5

Lesson appears in

UnitMaths / Ratio and proportion

Maths

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