Year 6 - Maths
Solve subtraction calculations mentally by using known facts
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 solve subtraction calculations mentally by using known facts.
Key Notes
- Compensation can be used to simplify subtraction calculations.
- Equivalence can be used to simplify subtraction calculations.
- A number line can be used to represent compensation and equivalence.
Vocabulary To Learn
- Minuend: The minuend is the number being subtracted from.
- Subtrahend: A subtrahend is a number subtracted from another.
- Partition: Partition is the act of splitting an object or value down into smaller parts.
- Adjust: When you adjust you make a change to a number. This is done to make a calculation easier to solve mentally.
Common Mistakes To Avoid
- Known facts in this lesson include complements and two-digit subtractions which some children may find challenging to recall fluently.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Compensation can be used to simplify subtraction calculations. Equivalence can be used to simplify subtraction calculations.
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: Known facts in this lesson include complements and two-digit subtractions which some children may find challenging to recall fluently. Correction: It's a good idea, if possible, to do some pre-teaching here to develop the confidence of the children who might find the known facts aspect provides extra cognitive load. Supplying scaffolds such as key bonds to 20 and 100 may also benefit.
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
- Use constant difference to balance equations and find unknowns Study Guide
- Use equivalence and compensation strategies to solve subtraction problems in a range of contexts Study Guide
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