Starter quiz
- What is meant by the sum?
- The answer to a multiplication question.
- A calculation.
- The difference between two numbers.
- The total when numbers are added together. ✓
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- 100 − 7 = ______
- '93' ✓
- What is the complement to 100 of 92?
- '8' ✓
- How far away is 97 from 100?
- '3' ✓
- Which of these base ten representations shows 68?
What number is being represented by base ten?- 543
- 345
- 354 ✓
- 453
- 435
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Exit quiz
- Match the expressions that are equal
- 29 + 17⇔30 + 16 ✓
- 20 + 35⇔19 + 36 ✓
- 13 + 79⇔12 + 80 ✓
- Use redistribution to find the missing number. ______ = 39 + 26
- '65' ✓
- Use redistribution to find the missing number. ______ = 530 + 190
- '720' ✓
- Use redistribution to find the missing number. ______ = 150 + 397
- '547' ✓
The base ten representation is showing a calculation being changed. The arrow shows some ones being redistributed. What is the transformed expression going to be?- 200 + 132 ✓
- 132 + 202
- 202 + 132
- 202 + 130
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- 156 ml of orange juice is mixed with 498 ml of pineapple juice. How many ml of juice is there altogether? ______ ml
- '654' ✓
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- If we subtract 1 from one addend, we must add one to the other added for the sum to remain the same
- When we redistribute, the total amount stays the same at all times
- Depending on the addends, we redistribute 1s or 10s
Common misconception
Pupils will sometimes remove or add ones or tens to one addend and forget to amend the other addend so that the calculation has been transformed but doesn't give the same sum as the original.
Encourage buddy checking of jottings as the children practise so that they can help each other to be reminded.
Keywords
Redistribute - Redistribution is a way of transforming a sum to make it easier to calculate mentally.
Inverse - The inverse is the opposite or reverse operation. For example, subtraction is the inverse operation of addition.
Efficient - Being efficient means finding a way to solve a problem quickly whilst also maintaining accuracy.
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