When the denominator of one fraction is a multiple of the denominator of another fraction, we can say these fractions are related fractions.

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

Explain how to subtract related unit fractions

Maths

Explain how to write a fraction in its simplest form

Reason about how to write a fraction in its simplest form

Use knowledge of fractions in their simplest form when solving addition and subtraction problems

Explain how to add related unit fractions with a representation or image

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

Use knowledge of adding and subtracting related unit fractions to solve problems

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

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

Add and subtract non-related fractions with different denominators

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. 

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

When one fraction has a denominator that is a multiple of another fraction, the fractions are called:

$$ {2} \over {12}$$ − $$ {1} \over {12}$$ = ____ 

$$ {3} \over {12}$$ − $$ {1} \over {12}$$ = ____ 

$$ {4} \over {12}$$ − $$ {1} \over {12}$$ = ____

$$ {5} \over {12}$$ − $$ {1} \over {12}$$ = ____ 

This image shows $$ {1} \over {4}$$ − $$ {1} \over {12}$$ = ____ Tick the equation which shows the equivalent related fraction.

$$ {2} \over {10}$$ − $$ {1} \over {10}$$ = ____ 

$$ {3} \over {15}$$ − $$ {1} \over {10}$$ = ____

$$ {4} \over {20}$$ − $$ {1} \over {10}$$ = ____

$$ {5} \over {25}$$ − $$ {1} \over {10}$$ = ____ 

This image shows $$ {1} \over {5}$$ − $$ {1} \over {10}$$ = ____ Tick the equation which shows the appropriate related fraction.

$$ {2} \over {10}$$ − $$ {1} \over {20}$$ = ___

$$ {3} \over {15}$$ − $$ {1} \over {20}$$ = ___

$$ {4} \over {20}$$ − $$ {1} \over {20}$$ = ___

$$ {5} \over {25}$$ − $$ {1} \over {20}$$ = ___

This image shows $$ {1} \over {5}$$ − $$ {1} \over {20}$$ = ____ Tick the equation which shows the appropriate related fraction.

$$ {1} \over {4}$$ − $$ {3} \over {4}$$ = ___

$$ {2} \over {8}$$ − $$ {1} \over {12}$$ = ___

$$ {3} \over {12}$$ − $$ {1} \over {12}$$ = ___

$$ {1} \over {8}$$ − $$ {1} \over {8}$$ = ___

Tick the correct equation once it has been adjusted to include the most appropriate related fraction. $$ {1} \over {4}$$ − $$ {1} \over {12}$$ = ___

Tick the correct solution: $$ {1} \over {8}$$ − $$ {1} \over {16}$$ = ___

Tick the fractions in their simplest form. 

What fraction of the whole shape is shaded?

Tick the sum in its simplest form.   $$ {3} \over {5}$$ + $$ {7} \over {5}$$ =

Tick the difference in its simplest form.    $$ {20} \over {4}$$ − $$ {5} \over {4}$$

Explain how to subtract related unit fractions

Lesson outcome