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# Mathematics Matters Lesson Accounts 31 - Finding all Factors of Numbers

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Created on 28 May 2008 by ncetm_administrator
Updated on 16 June 2008 by ncetm_administrator
 Mathematics Matters Lesson Accounts A collection of memorable mathematics lessons that conference and colloquia delegates had observed or taught which they felt were successful.  Each account refers to one or more of the values and principles in the report.

# Lesson Account 31 - Finding all Factors of Numbers

 Written by Lynne McClure Organisation Lynne McClure Consultancy Age/Ability Range Primary 9-10 mixed ability

Write some multiplication calculations so the answer is 120. Children recorded a couple on the board

Are there any more? How many more?

Children worked in pairs to generate more – encouraged to look at each others.
Children were asked to justify and agree inclusion of new solutions on board
‘Pupils were asked what else do you think we could find out?’
Children realised there are a limited number of two factor calculations – children suggested move from 2 factors to 3, then 4.
Shared ways of working, recorded results on separate pieces of paper stuck to board and rearranged into groups.

What were the critical moments?
Realising duplicates i.e. commutativity
Not needing to use 1 as a factor.
Discovered longest product was using prime numbers, in any order.

What mathematics was learnt? (on plan and off plan) and what is the evidence of learning?
Children realised how they could combine / break down / rearrange –commutativity etc.
Children realised that it didn’t matter where you started, you always got the same answer when reduced to prime factors.

How was that mathematics learnt?
Learning from each others answers / mistakes. Teacher played a guiding rather than a didactic role.

Other memorable outcomes
So excited – “that’s cool” – doesn’t matter what you do first, it always ends up the same. Can I do a really big one?

Resources
None mentioned

## Values & Principles

 Conceptual understanding and interpretations for representations Builds on the knowledge learners already have Encourages reasoning rather than ‘answer getting’ Uses rich, collaborative tasks Creates connections between topics both within and beyond mathematics and with the real world

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