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

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

Maths

In this unit pupils will explain how to write a fraction in its simplest form when solving addition and subtraction problems and how to add and subtract related fractions. In the future unit pupils will use their fraction sense to fraction addition, subtraction and comparison explaining how to compare pairs of non-related fractions by converting to common denominators and using fraction sense.

In the prior unit pupils used representations to describe and compare two fractions. They explained the relationship within families of equivalent fractions and used their knowledge of common equivalents to compare fractions with decimals. In this unit pupils will explain how to write a fraction in its simplest form when solving addition and subtraction problems. 

Addition and subtraction of fractions

Tick the related non-unit fraction for $$ {1} \over {4}$$

$$ {1} \over {4}$$    $$ {3} \over {12}$$

$$ {4} \over {6}$$    $$ {2} \over {12}$$

$$ {8} \over {15}$$    $$ {3} \over {5}$$

$$ {1} \over {3}$$ +  $$ {3} \over {15}$$

$$ {2} \over {3}$$  +  $$ {1} \over {15}$$ 

$$ {3} \over {3}$$  +  $$ {5} \over {15}$$

$$ {1} \over {3}$$ +  $$ {3} \over {10}$$

Tick the expression that matches this image.

$$ {8} \over {9}$$  − $$ {2} \over {18}$$ = ___

$$ {3} \over {7}$$ + $$ {3} \over {21}$$ = ___

$$ {1} \over {3}$$     $$ {2} \over {6}$$

$$ {1} \over {4}$$     $$ {3} \over {16}$$

$$ {2} \over {7}$$     $$ {4} \over {21}$$

$$ {1} \over {5}$$     $$ {1} \over {12}$$

$$ {4} \over {6}$$ +  $$ {1} \over {12}$$

$$ {3} \over {6}$$  +  $$ {1} \over {12}$$

$$ {1} \over {6}$$  +  $$ {1} \over {12}$$

$$ {1} \over {6}$$ +  $$ {5} \over {12}$$

Select the fraction which is $$ {8} \over {12}$$ in its simplest form.

Match each fraction to a related fraction.

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