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

Related fractions are when the denominator of one fraction is a multiple of the denominator of the other fraction.

Non-related fractions are when the denominator of one fraction is not a multiple of the denominator of the other fraction.

A multiple that is common between two or more numbers is known as a common multiple.

Add and subtract non-related fractions with different denominators

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

Explain how to subtract related unit fractions

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

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

neither denominator is a multiple of each other.

neither numerator is a multiple of each other.

Non-related fractions are fractions in which:

Tick the correct symbol to compare these expressions.

Tick the multiple that could be used as a common denominator for $$ {1} \over {5}$$ and $$ {1} \over {6}$$ 

Tick the correct solution for $$ {3} \over {4}$$ + $$ {2} \over {7}$$ = 

What number is missing from the equation?

one denominator is a multiple of the other denominator.

one numerator is a multiple of the other denominator.

What is the value of the numerator in the diagram?

$$ {1} \over {4}$$    $$ {2} \over {16}$$

$$ {1} \over {4}$$    $$ {5} \over {12}$$

$$ {3} \over {4}$$    $$ {4} \over {14}$$

$$ {1} \over {4}$$    $$ {1} \over {10}$$

What operation has taken place to scale the original fraction?

$$ {1} \over {3}$$ +  $$ {3} \over {18}$$ = ___

$$ {4} \over {5}$$ +  $$ {6} \over {20}$$ = ___ 

Add and subtract non-related fractions with different denominators

Lesson outcome