Add 2 and 3-digit numbers by redistributing
Lesson details
Learning outcome
I can add 2 and 3-digit numbers by redistributing.
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.
Teacher tip
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.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is meant by the sum?
Q2.100 − 7 =
Q3.What is the complement to 100 of 92?
Q4.How far away is 97 from 100?
Q5.Which of these base ten representations shows 68?
Q6.What number is being represented by base ten?
Assessment exit quiz
6 Questions
Q1.Match the expressions that are equal
30 + 16
19 + 36
12 + 80
Q2.Use redistribution to find the missing number. = 39 + 26
Q3.Use redistribution to find the missing number. = 530 + 190
Q4.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?
Q6.156 ml of orange juice is mixed with 498 ml of pineapple juice. How many ml of juice is there altogether? ml
To help you plan your 3 maths lesson on: Add 2 and 3-digit numbers by redistributing, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 3 maths lesson on: Add 2 and 3-digit numbers by redistributing, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 2 maths lessons from the Informal and mental strategies for adding and subtracting two 3-digit numbers unit, dive into the full primary maths curriculum, or learn more about lesson planning.