Year 3 - Maths
Solve multi-step addition and subtraction problems efficiently
Understand additive relationships and apply them to rearrange equations
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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 accurately and efficiently solve multi-step addition and subtraction problems. They will understand and explain how both addition and subtraction equations can be used to describe the same additive relationship.
Lesson Summary
You will learn to solve multi-step addition and subtraction problems efficiently.
Key Notes
- Addition and subtraction can be done in any order
- If you do the addition and subtraction in a different order, the answer will be the same
- The most efficient order can be chosen by looking at the numbers
Vocabulary To Learn
- Efficient: Working efficiently means finding a way to solve a problem quickly whilst also maintaining accuracy.
- Reorder: Reorder means arrange something in a different way.
Common Mistakes To Avoid
- Pupils may struggle when reordering equations where the addends and subtrahends are calculated first (e.g. 455 + 39 - 38)
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Addition and subtraction can be done in any order. If you do the addition and subtraction in a different order, the answer will be the same.
2. Use this key word in a maths sentence and explain it clearly. 'Efficient'
Working efficiently means finding a way to solve a problem quickly whilst also maintaining accuracy. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils may struggle when reordering equations where the addends and subtrahends are calculated first (e.g. 455 + 39 - 38). Correction: Give pupils opportunities to explore the relationship between the addend and subtrahend. They could calculate the answers to problems where the subtrahend is one less than the addend (e.g. 45 + 10 - 9). Can they see a pattern in their answers?
More Lessons In This Unit
- Develop understanding of the relationship between addition and subtraction Study Guide
- Identify knowns and unknowns in addition equations Study Guide
- Identify knowns and unknowns in subtraction equations Study Guide
- Solve one and two-step problems in different contexts Study Guide
- Solve problems using bar charts, pictograms and tables Study Guide
- Understand why the order of addition and subtraction steps can be chosen Study Guide
- Use the additive relationship to rearrange addition equations Study Guide
- Use the additive relationship to rearrange and solve equations Study Guide
- Use the additive relationship to rearrange subtraction equations Study Guide
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