Year 3 - Maths
Use the additive relationship to rearrange and solve equations
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 use the additive relationship to rearrange and solve equations.
Key Notes
- When a whole is missing, add the parts together.
- To find a missing part, subtract the other part from the whole.
- Rearrange the equation to make it easier to calculate the missing number.
Vocabulary To Learn
- equation: An equation shows that one number or calculation is equal to another.
- rearrange: Rearrange means to change an equation. It could mean moving the parts or the whole or changing it from an addition into a subtraction equation.
Common Mistakes To Avoid
- Pupils may use the wrong operation to find missing numbers, adding when they should be subtracting or vice versa.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
When a whole is missing, add the parts together. To find a missing part, subtract the other part from the whole.
2. Use this key word in a maths sentence and explain it clearly. 'equation'
An equation shows that one number or calculation is equal to another. 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 use the wrong operation to find missing numbers, adding when they should be subtracting or vice versa. Correction: Encourage pupils to draw bar models, focusing on the whole in the problem. They should also write problems, understanding where the missing number is and rearranging equations so that they can calculate the 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 multi-step addition and subtraction problems efficiently 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 subtraction equations Study Guide
Browse all guides in the Year 3 Maths guide library.