Study Hub

Study Guides

This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.

Back to Study HubBrowse Year 4 Maths Guides

Year 4 - Maths

Choose efficient approaches when subtracting mixed numbers

Efficient strategies for adding and subtracting mixed numbers (crossing a whole)

Unit Summary

In this unit pupils will add mixed numbers. They will subtract a proper fraction from a mixed number and subtract a mixed number from a mixed number explaining which strategy is most efficient.

Lesson Summary

You will learn to choose efficient approaches when subtracting mixed numbers.

Key Notes

  • Partitioning is a strategy that can be used to subtract mixed numbers.
  • When partitioning, the whole number part and the fractional part of the minuend must be greater than the subtrahend's.
  • Using number-sense can support us to determine the most efficient method to use when subtracting from mixed numbers.

Vocabulary To Learn

  • Mixed number: A mixed number is a whole number and a fraction combined.
  • Minuend: The minuend is the first number in a subtraction. The number from which another number is to be subtracted.
  • Subtrahend: The subtrahend is the number that is to be subtracted. The second number in a subtraction.

Common Mistakes To Avoid

  • When partitioning to subtract, children may partition correctly but then may subtract incorrectly by swapping the order of the fractional parts being subtracted.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

Partitioning is a strategy that can be used to subtract mixed numbers. When partitioning, the whole number part and the fractional part of the minuend must be greater than the subtrahend's.

2. Use this key word in a maths sentence and explain it clearly. 'Mixed number'

A mixed number is a whole number and a fraction combined. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: When partitioning to subtract, children may partition correctly but then may subtract incorrectly by swapping the order of the fractional parts being subtracted. Correction: Is partitioning efficient for this subtraction where the fractional part of the subtrahend is greater than that of the minuend? It may be more efficient to 'find the difference' by counting on.

More Lessons In This Unit

Browse all guides in the Year 4 Maths guide library.