Add and subtract fractions with the same denominator in a range of contexts | Maths

Starter quiz

Which of these definitions describes the subtrahend?

A number subtracted from another number. ✓

The number being subtracted from.

The result after subtracting one number from another.
Which number is the minuend in the following equation? 14 − 6 = 8

14 ✓

6

8
What addition is being shown by this number line?

30 = 20 + 50

50 + 30 = 20

30 + 20 = 50 ✓

30 + 50 = 20
Each marble in a bag is $\frac{1}{10}$ of the whole bag. How many marbles are there in the bag?

1

10 ✓

12

13
$The bar model shows four equal parts of the whole. What fraction can be used to label this?$

The bar model shows four equal parts of the whole. What fraction can be used to label this?

$\frac{1}{2}$

$\frac{1}{3}$

$\frac{1}{4}$ ✓
Select the correct sum. $\frac{2}{12}$ + $\frac{7}{12}$ = ___

$\frac{9}{12}$ ✓

$\frac{5}{12}$

$\frac{9}{24}$

$\frac{14}{12}$

Exit quiz

Choose the correct ending for this sentence. When adding or subtracting fractions with the same denominator, __________

add the numerators and add the denominators.

the denominator stays the same and the numerators are used for the calculations. ✓
$\frac{4}{10}$ + $\frac{5}{10}$ − $\frac{3}{10}$ = ___

$\frac{5}{10}$

$\frac{6}{10}$ ✓

$\frac{7}{10}$

$\frac{8}{10}$
Laura had a water bottle that was $\frac{9}{10}$ full. She drank $\frac{4}{10}$ of the bottle and then topped it up by $\frac{2}{10}$ What will the denominator of your answer be?

'10' ✓
Laura had a water bottle that was $\frac{9}{10}$ full. She drank $\frac{4}{10}$ of the bottle and then topped the bottle up by $\frac{2}{10}$ How much water is left in the bottle?

$\frac{9}{10}$

$\frac{5}{10}$

$\frac{7}{10}$ ✓

$\frac{7}{20}$
Sam is making juice. First, she adds in $\frac{10}{15}$ of apple juice. Then, she adds in $\frac{3}{15}$ of orange juice and pours out $\frac{9}{15}$ of the mix. What fraction is left?

$\frac{3}{15}$

$\frac{4}{15}$ ✓

$\frac{5}{15}$
Which expressions have a total greater than $\frac{5}{12}$ ?

$\frac{9}{12}$ − $\frac{3}{12}$ ✓

$\frac{2}{12}$ + $\frac{3}{12}$

$\frac{3}{12}$ + $\frac{4}{12}$ ✓

$\frac{8}{12}$ − $\frac{4}{12}$

Worksheet

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Lesson Details

Key learning points

If fractions have the same denominator they can be added or subtracted.
Number lines can represent addition and subtraction of fractions with the same denominator.
When you add or subtract fractions with the same denominator you add or subtract the numerators.

Common misconception

Children might still try to add or subtract the denominators as well due to a misunderstanding about the denominator showing what unit-fraction is being used for calculation.

By this stage, buddy checking can be useful. Get the children to check each other periodically but ensure that children can also explain why this is incorrect.

Keywords

Minuend - The minuend is the number being subtracted from.
Subtrahend - A subtrahend is a number subtracted from another. There can be more than one.
Numerator - A numerator is the top number in a fraction. It shows how many parts we have.
Denominator - A denominator is the bottom number in a fraction. It shows how many parts a whole has been divided into.