Year 2 - Maths
Explain how doubling and halving are related
Multiplying by 2, doubling and halving (factors and products)
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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 learn how multiplication with 2 as a factor relates to doubling and how we can see halving as the inverse of doubling, deriving the related halving fact from a known double.
Lesson Summary
You will learn to explain how doubling and halving are related.
Key Notes
- If double 4 is 8, then half of 8 is 4
- Halving means to partition the number into two equal groups.
- Halving is the inverse of doubling.
- Whether doubling or halving, we can also see these as our 2 times tables facts.
Vocabulary To Learn
- Double / Doubling: To become twice as many / to multiply by two.
- Half / Halving: One of two equal parts of a whole. To divide into two equal parts.
Common Mistakes To Avoid
- Children may inaccurately recall related doubling facts to solve halving problems.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
If double 4 is 8, then half of 8 is 4. Halving means to partition the number into two equal groups.
2. Use this key word in a maths sentence and explain it clearly. 'Double / Doubling'
To become twice as many / to multiply by two. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Children may inaccurately recall related doubling facts to solve halving problems. Correction: Represent each problem as a bar model (as the whole and two equal parts) before solving. Encourage children to check that the two equal parts are equal to the whole.
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