New
New
Add 2 and 3-digit numbers by redistributing
I can add 2 and 3-digit numbers by redistributing.
Lesson 3 of 10
New
New
- Year 3
Add 2 and 3-digit numbers by redistributing
I can add 2 and 3-digit numbers by redistributing.
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
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.
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.
This strategy is shown with practical resources and jottings but the end goal is for the children be able to do it mentally so try to reduce such supports as quickly as possible.
Teacher tip
Licence
This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is meant by the sum?
What is meant by the sum?
The answer to a multiplication question.
A calculation.
The difference between two numbers.
Q2.100 − 7 =
100 − 7 =
Q3.What is the complement to 100 of 92?
What is the complement to 100 of 92?
Q4.How far away is 97 from 100?
How far away is 97 from 100?
Q5.Which of these base ten representations shows 68?
Which of these base ten representations shows 68?
Q6.What number is being represented by base ten?
What number is being represented by base ten?
543
345
453
435
Assessment exit quiz
6 Questions
Q1.Match the expressions that are equal
Match the expressions that are equal
Q2.Use redistribution to find the missing number. = 39 + 26
Use redistribution to find the missing number. = 39 + 26
Q3.Use redistribution to find the missing number. = 530 + 190
Use redistribution to find the missing number. = 530 + 190
Q4.Use redistribution to find the missing number. = 150 + 397
Use redistribution to find the missing number. = 150 + 397
Q5.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?
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?
132 + 202
202 + 132
202 + 130
Q6.156 ml of orange juice is mixed with 498 ml of pineapple juice. How many ml of juice is there altogether? ml
156 ml of orange juice is mixed with 498 ml of pineapple juice. How many ml of juice is there altogether? ml
