Year 3 - Maths
Add on fractions with the same denominator
Composition of non-unit fractions: addition and subtraction
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will use repeated addition of a unit fraction to form a non-unit fraction. They will compare non-unit fractions with the same denominator. They will add and subtract fractions with the same denominator.
Lesson Summary
You will learn to add on fractions with the same denominator.
Key Notes
- If fractions have the same denominator they can be added on.
- 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.
Vocabulary To Learn
- 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 Mistakes To Avoid
- When adding fractions with the same denominator many children may try and add both the numerator and denominator.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
If fractions have the same denominator they can be added on. If 2 plus 3 is equal to 5 then 2 one sevenths plus 3 one sevenths is equal to 5 one sevenths.
2. Use this key word in a maths sentence and explain it clearly. 'Units'
The unit is one of something that defines the 'one' you are counting in. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When adding fractions with the same denominator many children may try and add both the numerator and denominator. Correction: This is a misunderstanding of the unitisation. Practise counting in different set of objects such as cubes, counters, children. Move children on to counting in fractions and explain that this is simply a different unit, shown by the denominator.
More Lessons In This Unit
- Add and subtract fractions with the same denominator in a range of contexts Study Guide
- Add fractions with the same denominator Study Guide
- Add fractions with the same denominator and generalise the rule Study Guide
- Explain that addition and subtraction of fractions are inverse operations Study Guide
- Substitute a fraction representing a whole to solve subtraction problems Study Guide
- Subtract fractions from a whole by converting the whole to a fraction Study Guide
- Subtract fractions with the same denominator Study Guide
- Use repeated addition of a unit fraction to form 1 Study Guide
- Use repeated addition of a unit fraction to form a non-unit fraction Study Guide
Browse all guides in the Year 3 Maths guide library.