Choose the most efficient strategy to add two 3-digit numbers
I can choose the most efficient strategy to add two 3-digit numbers.
Choose the most efficient strategy to add two 3-digit numbers
I can choose the most efficient strategy to add two 3-digit numbers.
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Lesson details
Key learning points
- By looking carefully at the addends, we can choose the most efficient addition strategy.
- Sometimes an adjusting strategy is the most efficient.
- Sometimes a redistributing strategy is the most efficient.
- Sometimes a partitioning and bridging strategy is the most efficient.
Keywords
Partition - Partitioning is the act of splitting an object or value down into smaller parts.
Adjust - When you adjust you make a small change to a number. This can make a calculation easier to solve mentally.
Redistribute / redistribution - Redistribution is where part of one addend is moved to another addend.
Efficient - Working efficiently means finding a way to solve a problem quickly whilst also maintaining accuracy.
Common misconception
Pupils will often know one method, such as partitioning, and stick to it without trying any others. Sometimes, some pupils will be very reluctant to move away from written methods such as columns.
Reinforce the idea of bravery and courage to try new methods. Remind them that efficiency is partly about speed and they might find that other methods only become quick with practice!
To help you plan your year 3 maths lesson on: Choose the most efficient strategy to add two 3-digit numbers, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 3 maths lesson on: Choose the most efficient strategy to add two 3-digit numbers, 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.
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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.
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Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is the number pair to ten for 6?
Q2.What is the number pair to 100 for 30?
Q3.Each bundle contains ten straws. How many straws are there altogether?
Q4.Match the units to their value.
30
60
4
100
Q5.Fill in the missing number in this sequence: 70, 80, 90, 100, , 120, 130, 140
Q6.Fill in the missing number in this sequence: 170, 175, 180, 185, , 195, 200, 205
Assessment exit quiz
6 Questions
Q1.102 + 130 = 232 is calculated using partitioning, adjustment or redistribution and represented using base ten. Which of the three methods is shown?
Q2.102 + 130 = 232 is calculated using partitioning, adjustment or redistribution and represented using base ten. Which of the three methods is shown?
Q3.102 + 130 = 232 is calculated using partitioning, adjustment or redistribution and represented using base ten. Which of the three methods is shown?
Q4.Which of these two words describes how a solution is found 'efficiently'?
Q5.Which method would be best for solving 507 + 260?
Q6.Match the equations with the method which was most efficient for finding the sum.
Adjustment
Redistribution
Partitioning