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Year 5

Find the whole when the size of a non-unit fraction is known

I can find the whole when the size of a non-unit fraction is known.

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New
New
Year 5

Find the whole when the size of a non-unit fraction is known

I can find the whole when the size of a non-unit fraction is known.

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Lesson details

Key learning points

  1. This is __ of the whole so one part of the whole is __
  2. There will be __ of these parts in the whole
  3. If you work out the size of a unit fraction from the non-unit fraction, you can work out the size of the whole

Keywords

  • Represent - To represent something means to show something in a different way. The same thing can be shown using multiple representations.

  • Unit fraction - A unit fraction is a fraction that has a numerator of one.

  • Non-unit fraction - A non-unit fraction is a fraction that has a numerator greater than one.

  • Denominator - The denominator is the bottom number in a fraction.

  • Numerator - The numerator is the top number in a fraction.

Common misconception

Pupils multiply the non-unit fraction by the denominator to create the whole.

Ensure pupils spend time breaking down non-unit fractions back into unit fractions. Encourage pupils to recognise this as two stages. Firstly, find the unit fraction. Secondly, re-create the whole.


To help you plan your year 5 maths lesson on: Find the whole when the size of a non-unit fraction is known, download all teaching resources for free and adapt to suit your pupils' needs...

Ensure you give additional time for pupils to practise, eventually moving away from representing the mathematics with a bar model every time. Whilst it is good for pupils to represent the maths in a way that makes sense to them, pupils should also be encouraged to calculate these problems mentally.
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Lesson video

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6 Questions

Q1.
Complete: $$ \frac{1}{4} $$ + $$ \frac{1}{4} $$ + $$ \frac{1}{4} $$ + $$ \frac{1}{4} $$ =
Correct Answer: 1, 1 whole, one whole, four quarters
Q2.
The image represents $$ \frac{3}{4} $$ of the shape. Tick the image that shows $$ \frac{1}{4} $$
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Q3.
The image represents $$ \frac{2}{5} $$ of the whole. Tick the image that shows $$ \frac{1}{5} $$
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q4.
The part of the image shown by the arrow represents $$ \frac{6}{8} $$ How many intervals would represent $$ \frac{1}{8} $$
An image in a quiz
Correct answer: 1
2
3
4
Q5.
The image represents $$ \frac{1}{4} $$ of the whole. How many cubes would be needed to make the whole? cubes
An image in a quiz
Correct Answer: 8
Q6.
The image represents $$ \frac{3}{5} $$ of the whole. How many circles would be needed to represent the whole?
An image in a quiz
Correct Answer: 20, twenty

6 Questions

Q1.
Think about a fraction. The __________ tells us how many equal parts the whole has been divided into.
numerator
Correct answer: denominator
whole fraction
Q2.
The image represents $$ \frac{2}{5} $$ of the whole. Tick the images that could represent the whole.
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Q3.
Tick the image that represents the whole collection. Sam says ‘This is two-quarters of the apples Mum bought on her shopping trip.’
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q4.
Which line would have the largest whole?
An image in a quiz
An image in a quiz
An image in a quiz
Correct Answer: An image in a quiz
An image in a quiz
Q5.
If $$ \frac{5}{8} $$ of a number is 45, what is the number?
Correct Answer: 72
Q6.
If $$ \frac{3}{5} $$ of a number is 330, what is the number?
Correct Answer: 550