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

Explain with and without images how to add and subtract related non-unit fractions bridging a whole

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

What is the value of the numerator in this diagram?

What is the value of the missing numerator?

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

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

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

$$ {9} \over {12}$$ +  $$ {4} \over {12}$$ 

Tick the expressions that represent the shaded parts of these bars being added together.

$$ 1{{4} \over {12}}$$  − $$ {10} \over {24}$$ =

$$ 1 {{3} \over {6}}$$ − $$ {8} \over {12}$$ + $$ {4} \over {24}$$ =

12 inches is equivalent to one __________.

$$ {1} \over {5}$$    $$ {2} \over {9}$$ 

$$ {1} \over {4}$$    $$ {7} \over {12}$$

$$ {3} \over {6}$$    $$ {4} \over {24}$$

$$ {1} \over {5}$$    $$ {1} \over {25}$$ 

Select the fraction which is $$ {6} \over {9}$$ in its simplest form.

$$ {1} \over {5}$$ +  $$ {3} \over {15}$$ = ___ 

Match each fraction to a related fraction.

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