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# Mathematics Matters Lesson Accounts 3 - Children Describing their Solutions to Digit Additions and Subtractions in Various Forms

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Created on 27 May 2008 by ncetm_administrator
Updated on 25 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 3 - Children describing their solutions to digit additions and subtractions in various forms

 Written by Alison Brunt Organisation NCETM Age/Ability Range Year 4

This was done in stages with children asked first to describe in words how they would work out the answer to their calculation mentally. Children worked in pairs with 2 pairs having the same calculation.

Methods were scribed on the IWB and similarities and differenced between approaches were discussed.

This process was repeated for the same calculations with children asked to represent them on i) a numberline ii) using a written method.

The task was sustained through paired work – discussing strategies and sharing with another pair.

The lesson was concluded with an appreciation by the teacher that further work on the use of number lines was needed in the next session. There was discussion around strategies that were best suited to particular calculations.

What were the critical moments?
Children being required to focus their explanation in a particular form and recognising the difficulty of this.

Teacher being made aware of a fundamental lack of understanding in most of the children in terms of being able to represent calculations using a number line or other methods.

What mathematics was learnt? (on plan and off plan) and what is the evidence of learning?
Children learnt that there are various ways to explain their MATHEMATICS, that some are more easily explained than others and that some approaches suit some calculations better than others. Evidenced by their comments and sharing with partners.

How was that mathematics learnt?
The learning came from ‘doing’ calculations in a different way – emphasis on explaining and sharing ideas rather than just practising.

Other memorable outcomes
The issue of understanding the use of number-lines. These very able children struggled to model addition on a number line – those that attempted it actually did subtractions using the counting method.

Resources
The IMB allowed for explanations of mental strategies to be scribed and then physically sorted into explanations that were very similar and led to the development of greater precision in language.

## Values & Principles

 Conceptual understanding and interpretations for representations Builds on the knowledge learners already have Encourages reasoning rather than ‘answer getting’ Uses resources, including technology, in creative and appropriate ways

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