Year 3 - Maths
Subtract 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 subtract fractions with the same denominator.
Key Notes
- If 5 subtract 2 is equal to 3 then 5 one sevenths subtract 2 one sevenths is equal to 3 one sevenths.
- To subtract fractions with the same denominator you subtract the numerators using the language of unitising.
- If fractions have the same denominator they can be subtracted.
Vocabulary To Learn
- 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.
Common Mistakes To Avoid
- Children will rush to subtract both the numerator and the denominator when performing a subtraction of fractions with either structure in the lesson.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
If 5 subtract 2 is equal to 3 then 5 one sevenths subtract 2 one sevenths is equal to 3 one sevenths. To subtract fractions with the same denominator you subtract the numerators using the language of unitising.
2. Use this key word in a maths sentence and explain it clearly. 'Minuend'
The minuend is the number being subtracted from. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Children will rush to subtract both the numerator and the denominator when performing a subtraction of fractions with either structure in the lesson. Correction: Reinforce the concept of the unit being the fraction which is denoted by the denominator. Get children to perform subtractions using real life objects before moving them onto using fractions instead, perhaps using unit fractions to begin with.
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
- Add on fractions with the same denominator 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
- 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.