Explain how to add related unit fractions without a representation or image | Maths

Starter quiz

$What fraction of the shape is shaded?$

What fraction of the shape is shaded?
- ${4} \over {24}$ ✓
- ${4} \over {20}$
- ${1} \over {4}$
- 4
$What fraction of the shape is shaded?$

What fraction of the shape is shaded?
- ${1} \over {24}$
- ${1} \over {16}$
- ${8} \over {16}$
- ${8} \over {24}$ ✓
Tick the fractions in their simplest form
- ${7} \over {14}$
- ${9} \over {12}$
- ${2} \over {7}$ ✓
- ${1} \over {3}$ ✓
Tick the sum in its simplest form. ${5} \over {8}$ + ${2} \over {8}$ =
- ${7} \over {8}$ ✓
- ${7} \over {4}$
- ${3} \over {8}$
- ${1} \over {4}$
$What fraction of the whole shape is shaded?$

What fraction of the whole shape is shaded?
- ${10} \over {20}$ ✓
- ${3} \over {10}$
- ${1} \over {2}$ ✓
- ${10} \over {10}$
Tick the difference in its simplest form. ${18} \over {6}$ − ${4} \over {6}$
- ${14} \over {6}$
- $2 {{2} \over {6}}$
- ${7} \over {3}$ ✓
- $2 {{1} \over {3}}$ ✓

Exit quiz

Fractions can be called ‘related fractions’ if:
- they have the same number for the numerator.
- they have the same number for the denominator.
- they have the same numerator and denominator.
- one has a denominator that is a multiple of the other fraction’s denominator. ✓
Fractions have a common denominator when:
- they have the same number for the numerator.
- they have the same number for the denominator. ✓
- they have the same numerator and denominator.
- one has a denominator that is a multiple of the other fraction’s denominator.
Tick the ‘related fractions’ of ${1} \over {6}$
- ${2} \over {22}$
- ${1} \over {7}$
- ${2} \over {12}$ ✓
- ${3} \over {12}$ ✓
- ${1} \over {24}$ ✓
Tick the statements that are true: The sum of ${1} \over {4}$ + ${1} \over {12}$ will be:
- greater than one half.
- less than one half. ✓
- equal to one half.
- greater than ${2} \over {12}$ ✓
- greater than ${2} \over {4}$
$What number have the numerator and denominator been multiplied by to create a related fraction? <span class="blank">______</span>$

What number have the numerator and denominator been multiplied by to create a related fraction? ______
- '5' ✓
Tick the correct answer. ${1} \over {5}$ + ${3} \over {20}$ = ___
- ${4} \over {20}$
- ${7} \over {20}$ ✓
- ${4} \over {25}$
- ${7} \over {25}$
- ${4} \over {100}$

Worksheet

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Presentation

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Lesson Details

Key learning points

Common multiples help you to convert a fraction to a common denominator.
When adding fractions the denominators have to be the same.
The language of unitising helps you to add fractions with the same denominators.
When adding fractions with the same denominators you just add the numerators,

Common misconception

Pupils try to add both the numerators and both the denominators in order to find the sum.

Spend time converting related fractions so that the denominators are common. Use analogies such as adding cats and dogs and needing to rename them as animals or pets to help highlight the need for a common counting unit (or common denominator).

Keywords

Related fractions - When the denominator of one fraction is a multiple of the denominator of another fraction, we can say these fractions are related fractions.
Common denominator - When two or more fractions share the same denominator, you can say they have a common denominator.