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

      I can explain how to add related unit fractions with and without a representation or image.

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      Lesson 5 of 10
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      • Year 6

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

      I can explain how to add related unit fractions with and without a representation or image.

      Lesson details

      Key learning points

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

      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.

      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).

      Ensure time is given to identifying whether fractions are related or not. Once again, this will be dependent on pupils' times table knowledge, so where this may be an issue, provide pupils with fractions that support them to see the structure rather than focus on tables knowledge.
      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 fraction of the shape is shaded?

      An image in a quiz
      Correct answer: $$ {4} \over {24}$$
      $$ {4} \over {20}$$
      $$ {1} \over {4}$$
      4

      Q2.
      What fraction of the shape is shaded?

      An image in a quiz
      $$ {1} \over {24}$$
      $$ {1} \over {16}$$
      $$ {8} \over {16}$$
      Correct answer: $$ {8} \over {24}$$

      Q3.
      Tick the fractions in their simplest form

      $$ {7} \over {14}$$
      $$ {9} \over {12}$$
      Correct answer: $$ {2} \over {7}$$
      Correct answer: $$ {1} \over {3}$$

      Q4.
      Tick the sum in its simplest form. $$ {5} \over {8}$$ + $$ {2} \over {8}$$ =

      Correct answer: $$ {7} \over {8}$$
      $$ {7} \over {4}$$
      $$ {3} \over {8}$$
      $$ {1} \over {4}$$

      Q5.
      What fraction of the whole shape is shaded?

      An image in a quiz
      Correct answer: $$ {10} \over {20}$$
      $$ {3} \over {10}$$
      Correct answer: $$ {1} \over {2}$$
      $$ {10} \over {10}$$

      Q6.
      Tick the difference in its simplest form. $$ {18} \over {6}$$ − $$ {4} \over {6}$$

      $$ {14} \over {6}$$
      $$2 {{2} \over {6}}$$
      Correct answer: $$ {7} \over {3}$$
      Correct answer: $$ 2 {{1} \over {3}}$$

      Assessment exit quiz

      Download quiz pdf

      6 Questions

      Q1.
      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.
      Correct answer: one has a denominator that is a multiple of the other fraction’s denominator.

      Q2.
      Fractions have a common denominator when:

      they have the same number for the numerator.
      Correct answer: 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.

      Q3.
      Tick the ‘related fractions’ of $$ {1} \over {6}$$

      $$ {2} \over {22}$$
      $$ {1} \over {7}$$
      Correct answer: $$ {2} \over {12}$$
      Correct answer: $$ {3} \over {12}$$
      Correct answer: $$ {1} \over {24}$$

      Q4.
      Tick the statements that are true: The sum of $$ {1} \over {4}$$ + $$ {1} \over {12}$$ will be:

      greater than one half.
      Correct answer: less than one half.
      equal to one half.
      Correct answer: greater than $$ {2} \over {12}$$
      greater than $$ {2} \over {4}$$

      Q5.
      What number have the numerator and denominator been multiplied by to create a related fraction?

      An image in a quiz
      Correct Answer: 5

      Q6.
      Tick the correct answer. $$ {1} \over {5}$$ + $$ {3} \over {20}$$ = ___

      $$ {4} \over {20}$$
      Correct answer: $$ {7} \over {20}$$
      $$ {4} \over {25}$$
      $$ {7} \over {25}$$
      $$ {4} \over {100}$$

      Lesson appears in

      UnitMaths / Addition and subtraction of fractions

      Maths

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