Year 6 - Maths
Use constant difference to balance equations and find unknowns
Use equivalence and compensation to simplify and solve subtraction problems
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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 explain how increasing or decreasing the minuend affects the difference and solve subtraction calculations mentally by using known facts explaining how adjusting the minuend can make mental calculation easier.
Lesson Summary
You will learn to use the same difference rule to balance equations.
Key Notes
- If I add __ to the minuend and add the same number to the subtrahend, the difference stays the same.
- If I subtract __ from the minuend and add the same number to the subtrahend, the difference stays the same.
- A number line can be used to represent the 'same difference' generalization.
Vocabulary To Learn
- Minuend: The minuend is the number being subtracted from.
- Subtrahend: A subtrahend is a number subtracted from another.
- Difference: The difference is the result after subtracting one number from another.
- Constant: A constant is a quantity that has a fixed value that does not change or vary, such as a number.
- Unknown: An unknown is a quantity that has a set value but it is represented by a symbol or letter.
Common Mistakes To Avoid
- Lots of pupils will want to calculate the value of the expression with the known parts in order to calculate the unknown part without considering a more efficient approach.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
If I add __ to the minuend and add the same number to the subtrahend, the difference stays the same. If I subtract __ from the minuend and add the same number to the subtrahend, the difference stays the same.
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: Lots of pupils will want to calculate the value of the expression with the known parts in order to calculate the unknown part without considering a more efficient approach. Correction: Calculating the value of one expression is efficient with simple numbers but encourage the children to try and compare the parts instead. As the numbers get harder, calculating the expression becomes much less efficient.
More Lessons In This Unit
- Calculate the difference using knowledge of an adjusted subtrahend: difference structure Study Guide
- Explain and represent constant difference for subtraction Study Guide
- Explain how adjusting the minuend can make mental calculation easier Study Guide
- Explain how adjusting the subtrahend affects the difference: partitioning Study Guide
- Explain how adjusting the subtrahend affects the difference: reduction structure Study Guide
- Explain how constant difference can make written calculations more efficient Study Guide
- Explain how increasing or decreasing the minuend affects the difference Study Guide
- Solve subtraction calculations mentally by using known facts Study Guide
- Use equivalence and compensation strategies to solve subtraction problems in a range of contexts Study Guide
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