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Lesson 3 of 10
New
New
- Year 3
Add fractions with the same denominator
I can add fractions with the same denominator.
Lesson details
Key learning points
- If fractions have the same denominator they can be added.
- If 2 plus 3 is equal to 5 then 2 one sevenths plus 3 one sevenths is equal to 5 one sevenths.
- To add fractions with the same denominator you use the language of unitising.
Keywords
Units - The unit is one of something that defines the ‘one’ you are counting in.
Denominator - A denominator is the bottom number in a fraction. It shows how many parts a whole has been divided into.
Numerator - A numerator is the top number in a fraction. It shows how many parts we have.
Common misconception
Typically, many children add both the numerators and denominators together to get the sum.
Pupils need to grasp units and unitising. Get them to move around the classroom/school performing simple additions with different sets of objects. Revisit fractions explaining that they're using unit fractions and this is shown by the denominator.
You may want to provide the children with the chance to create their own representation of the watermelon slice calculation in the first lesson cycle before discussing what the Oak characters come up with. This will give ownership to the class.
Teacher tip
Licence
This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which of these definitions describes an addend?
Which of these definitions describes an addend?
Correct answer: A number added to another number.
A number added to another number.
All of the parts added together.
Q2.What is the missing number in this bar model?
What is the missing number in this bar model?
Correct Answer: 3, three
3, three
Q3.What addition is being shown by this number line?
What addition is being shown by this number line?
2 + 3 = 5
Correct answer: 5 = 3 + 2
5 = 3 + 2
2 + 5 = 3
3 = 2 + 5
Q4.A melon is cut into eight equal parts. What fraction is each part?
A melon is cut into eight equal parts. What fraction is each part?
$$ \frac{2}{8} $$
Correct answer: $$ \frac{1}{8} $$
$$ \frac{1}{8} $$
$$ \frac{1}{6} $$
$$ \frac{1}{7} $$
Q5.How could we show the whole represented in this bar model using fraction notation?
How could we show the whole represented in this bar model using fraction notation?
Correct answer: $$ \frac{5}{5} $$
$$ \frac{5}{5} $$
$$ \frac{4}{4} $$
$$ \frac{3}{3} $$
$$ \frac{2}{2} $$
Q6.When the numerator and denominator are the same, what do we know about the value of the fraction?
When the numerator and denominator are the same, what do we know about the value of the fraction?
Correct answer: It’s equivalent to one whole.
It’s equivalent to one whole.
Correct answer: It’s equivalent to 1
It’s equivalent to 1
It’s equivalent to 0
Assessment exit quiz
6 Questions
Q1.Look at the picture. What is the unit of this addition?
Look at the picture. What is the unit of this addition?
Ones
Correct answer: Bears
Bears
Numerals
Q2.Look at the image. What is the missing label marked with a question mark?
Look at the image. What is the missing label marked with a question mark?
addend
Correct answer: sum
sum
part
Q3.What addition is being represented on this number line?
What addition is being represented on this number line?
$$ \frac{6}{8} $$ + $$ \frac{3}{8} $$ = $$ \frac{3}{8} $$
$$ \frac{1}{8} $$ + $$ \frac{5}{8} $$ = $$ \frac{6}{8} $$
$$ \frac{6}{8} $$ + $$ \frac{5}{8} $$ = $$ \frac{1}{8} $$
Correct answer: $$ \frac{3}{8} $$ + $$ \frac{3}{8} $$ = $$ \frac{6}{8} $$
$$ \frac{3}{8} $$ + $$ \frac{3}{8} $$ = $$ \frac{6}{8} $$
Q4.Which is the correct sum for this equation?
$$ \frac{3}{9} $$ + $$ \frac{2}{9} $$ = ___
Which is the correct sum for this equation?
$$ \frac{3}{9} $$ + $$ \frac{2}{9} $$ = ___
$$ \frac{5}{18} $$
Correct answer: $$ \frac{5}{9} $$
$$ \frac{5}{9} $$
$$ \frac{1}{9} $$
Q5.Which is the correct sum for this equation?
___ = $$ \frac{2}{12} $$ + $$ \frac{6}{12} $$
Which is the correct sum for this equation?
___ = $$ \frac{2}{12} $$ + $$ \frac{6}{12} $$
$$ \frac{12}{24} $$
$$ \frac{8}{24} $$
Correct answer: $$ \frac{8}{12} $$
$$ \frac{8}{12} $$
Q6.Which equation matches the problem?
A pizza is cut into 6 slices. Sam eats three slices and Sofia eats one slice. What fraction of the pizza has been eaten?
Which equation matches the problem?
A pizza is cut into 6 slices. Sam eats three slices and Sofia eats one slice. What fraction of the pizza has been eaten?
Correct answer: $$ \frac{3}{6} $$ + $$ \frac{1}{6} $$ = $$ \frac{4}{6} $$
$$ \frac{3}{6} $$ + $$ \frac{1}{6} $$ = $$ \frac{4}{6} $$
$$ \frac{3}{6} $$ + $$ \frac{1}{6} $$ = $$ \frac{6}{6} $$
$$ \frac{6}{6} $$ + $$ \frac{1}{6} $$ = $$ \frac{4}{6} $$
