New
New
Year 6

Explain with and without an image how to add and subtract related non-unit fractions

I can explain with and without an image how to add and subtract related non-unit fractions

New
New
Year 6

Explain with and without an image how to add and subtract related non-unit fractions

I can explain with and without an image how to add and subtract related non-unit fractions

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Lesson details

Key learning points

  1. You can use knowledge of common multiples to convert fractions to an equivalent with a common denominator.
  2. In equivalent fractions, the numerators and denominators have been scaled up or down by the same factor.
  3. Fractions need to have the same denominator if you are to add and subtract them.
  4. When adding or subtracting fractions with the same denominators you just add or subtract the numerators,

Keywords

  • Common denominator - When two or more fractions share the same denominator, you can say they have a common denominator.

Common misconception

Pupils add or subtract the numerators and denominators from eachother to find the solution.

Ensure pupils don't move to abstract equations straight away until they are secure with how addition and subtraction of non-unit fractions can be represented pictorially. You can use unitised language: ___ fifths plus ___ fifths = ___ fifths.

They key for this lesson is for pupils to recognise the size of each part in relation to the whole. You could provide pupils with concrete examples of the whole and encourage pupils to use repeated shapes to make the whole and identify their values.
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).

Lesson video

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6 Questions

Q1.
Tick the non-unit fractions.
$$ {1} \over {3}$$
Correct answer: $$ {4} \over {7}$$
Correct answer: $$ {5} \over {4}$$
$$ {1} \over {8}$$
Q2.
Tick the largest fraction.
$$ {1} \over {4}$$
$$ {2} \over {7}$$
$$ {3} \over {6}$$
Correct answer: $$ {8} \over {9}$$
Q3.
Tick the pairs of related fractions.
Correct answer: $$ {1} \over {3}$$ $$ {2} \over {6}$$
Correct answer: $$ {1} \over {4}$$ $$ {3} \over {16}$$
Correct answer: $$ {2} \over {7}$$ $$ {4} \over {21}$$
$$ {1} \over {5}$$ $$ {1} \over {12}$$
Q4.
Tick the expression that matches this image.
An image in a quiz
$$ {4} \over {6}$$ + $$ {1} \over {12}$$
$$ {3} \over {6}$$ + $$ {1} \over {12}$$
Correct answer: $$ {1} \over {6}$$ + $$ {1} \over {12}$$
$$ {1} \over {6}$$ + $$ {5} \over {12}$$
Q5.
Select the fraction which is $$ {8} \over {12}$$ in its simplest form.
$$ {4} \over {6}$$
Correct answer: $$ {2} \over {3}$$
$$ {1} \over {12}$$
$$ {1} \over {8}$$
Q6.
Match each fraction to a related fraction.
Correct Answer:$$ {1} \over {3}$$,$$ {7} \over {21}$$

$$ {7} \over {21}$$

Correct Answer:$$ {1} \over {4}$$,$$ {8} \over {36}$$

$$ {8} \over {36}$$

Correct Answer:$$ {1} \over {5}$$,$$ {9} \over {55}$$

$$ {9} \over {55}$$

Correct Answer:$$ {1} \over {6}$$, $$ {24} \over {72}$$

$$ {24} \over {72}$$

6 Questions

Q1.
Tick the non-unit fractions.
$$ {1} \over {9}$$
Correct answer: $$ {2} \over {7}$$
Correct answer: $$ {3} \over {8}$$
$$ {1} \over {10}$$
Correct answer: $$ {8} \over {3}$$
Q2.
Tick the related non-unit fraction for $$ {1} \over {4}$$
$$ {1} \over {8}$$
$$ {1} \over {12}$$
Correct answer: $$ {3} \over {16}$$
$$ {12} \over {3}$$
Q3.
Tick the pairs of related fractions.
Correct answer: $$ {1} \over {4}$$ $$ {3} \over {12}$$
Correct answer: $$ {4} \over {6}$$ $$ {2} \over {12}$$
Correct answer: $$ {8} \over {15}$$ $$ {3} \over {5}$$
$$ {1} \over {6}$$ $$ {2} \over {4}$$
Q4.
Tick the expression that matches this image.
An image in a quiz
Correct answer: $$ {1} \over {3}$$ + $$ {3} \over {15}$$
$$ {2} \over {3}$$ + $$ {1} \over {15}$$
$$ {3} \over {3}$$ + $$ {5} \over {15}$$
$$ {1} \over {3}$$ + $$ {3} \over {10}$$
Q5.
$$ {8} \over {9}$$ − $$ {2} \over {18}$$ = ___
Correct answer: $$ {14} \over {18}$$
Correct answer: $$ {7} \over {9}$$
$$ {2} \over {9}$$
$$ {7} \over {18}$$
$$ {14} \over {9}$$
Q6.
$$ {3} \over {7}$$ + $$ {3} \over {21}$$ = ___
$$ {14} \over {21}$$
$$ {4} \over {21}$$
Correct answer: $$ {12} \over {21}$$
$$ {14} \over {42}$$
$$ {6} \over {28}$$