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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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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Share activities with pupils

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Lesson details

Key learning points

This is __ of the whole so one part of the whole is __
There will be __ of these parts in the whole
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.

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.

Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).