Choose the most efficient strategy to add two 3-digit numbers
Lesson details
Learning outcome
I can choose the most efficient strategy to add two 3-digit numbers.
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!
Teacher tip
Pupils will not always agree with the most efficient strategy selected on these slides. Efficiency is about speed and accuracy. Pupil's speed will develop with the strategy they feel most confident about. This is about mental addition so wherever possible get the children to do it in their heads.
Licence
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
To help you plan your 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 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.
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.