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Year 3

Add two 3-digit numbers using partitioning

I can add two 3-digit numbers using partitioning.

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New
New
Year 3

Add two 3-digit numbers using partitioning

I can add two 3-digit numbers using partitioning.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. Partitioning can be used to add 3-digit numbers
  2. Unitising means we can use known facts to add larger numbers. For example, 370 + 260 is equal to 37 tens add 26 tens.

Common misconception

Pupils may not understand that a tens counter has a value of ten. For example, they may think that 14 tens and 11 tens make 25 altogether, forgetting to convert 25 tens into 250.

Encourage counting in tens using counters to begin with. Move onto modelling questions using base ten so the children can count the tens blocks.

Keywords

  • Addend - An addend is a number added to another.

  • Sum - The sum means the total when the numbers are added together.

  • Unitising - Unisiting means treating groups that contain the same number of things as 'ones' or 'units'.

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 (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.
What is an addend?
An addend is a number multiplied by a number.
Correct answer: An addend is a number added to another.
An addend is a number subtracted from another.
Q2.
What should you add to 70 to make 100?
Correct Answer: 30, thirty, Thirty, 3 tens, three tens
Q3.
What would you add to 92 to make 100?
Correct Answer: 8, eight, Eight, 8 ones, eight ones
Q4.
92 + 14 =
Correct Answer: 106, one-hundred and six, one hundred and six, One hundred and six, One-hundred and six
Q5.
= 107 − 9
Correct Answer: 98, Ninety-eight, ninety-eight, Ninety eight, ninety eight
Q6.
The bucket balance has been filled with marbles and blocks. It is balanced. Which of these most closely represent the equation shown by the bucket balance?
An image in a quiz
2 + 2 = 2 + 2
2 + 3 = 2 + 3
Correct answer: 2 + 3 = 4 + 1
Correct answer: 3 + 2 = 1 + 4
3 + 3 = 2 + 4

Exit quiz

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6 Questions

Q1.
Which group has a different number of 'units'?
An image in a quiz
Correct Answer: Pandas, bears
Q2.
Match the units with their value.
Correct Answer:3 tens,30

30

Correct Answer:3 hundreds,300

300

Correct Answer:3 ones,3

3

Correct Answer:4 tens,40

40

Correct Answer:5 hundreds,500

500

Correct Answer:7 ones,7

7

Q3.
Match the expressions.
Correct Answer:4 + 5,4 ones + 5 ones

4 ones + 5 ones

Correct Answer:4 tens + 5 tens,40 + 50

40 + 50

Correct Answer:4 hundreds + 5 hundreds,400 + 500

400 + 500

Correct Answer:32 + 54,32 ones + 54 ones

32 ones + 54 ones

Correct Answer:32 tens + 54 tens,320 + 540

320 + 540

Correct Answer:450 + 390,45 tens + 39 tens

45 tens + 39 tens

Q4.
130 + 150 =
Correct Answer: 280, two hundred and eighty, 28 tens
Q5.
Match the expressions with the most relevant strategy for mental addition.
Correct Answer:407 + 380,Partitioning

Partitioning

Correct Answer:150 + 110,Unitising

Unitising

Q6.
= 211 + 450
Correct Answer: 661