Year 3 - Maths
Subtract fractions from a whole by converting the whole to a fraction
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 from a whole by converting the whole to a fraction.
Key Notes
- A fraction with the same numerator and denominator is equal to one whole.
- To subtract a fraction from a whole, convert the whole to a fraction with the same denominator as the subtrahend.
- The minuend and subtrahend have the same denominator to subtract easily.
- When the denominators are the same, you subtract the numerators using the language of unitising.
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 often find it difficult to understand the idea that any whole can be represented by a fraction with the same numerator and denominator.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
A fraction with the same numerator and denominator is equal to one whole. To subtract a fraction from a whole, convert the whole to a fraction with the same denominator as the subtrahend.
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 often find it difficult to understand the idea that any whole can be represented by a fraction with the same numerator and denominator. Correction: You might want to list down some different real life examples such as slices of pizza or pie, complete sets of sticker pages, full packs of pens/pencils. Label each example with fraction notation so the children get a firmer understanding.
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 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.