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What Makes A Good Resource - Teaching Negativity

This page has been archived. The content was correct at the time of original publication, but is no longer updated.
Created on 08 September 2009 by ncetm_administrator
Updated on 03 September 2010 by ncetm_administrator

What Makes a Good Resource

Teaching Negativity

Teaching Negativity - resource exampleTeacher comment:
I have been trying for over 10 years to find an approach to teaching the idea of a negative (or directed) number. I want to find an approach that allows students to develop and retain an understanding. I am quite clear that this does not mean they can just perform calculations with positive and negative numbers accurately; they need also to explain to me why?

In short I am searching for something that results in an understanding of the concept of “negativity”.


What I did:
I ask my students what makes for a happy classroom.  We talk about the balance of happy students and sad students. I then ask them individually how they would make the room more happy. The common response is to get more happy people into the room. However I was always looking out for the odd-ball or left field response of “get rid of the negative people.” If it hadn’t come, then I was ready to ask “without letting anyone else in the room how could we make it more happy?” Through this I develop the idea that subtracting negativeness causes an increase in the balance.
This approach seemed to work well both as a group activity, but also on an individual level. Every human has a state of happiness, and all students can transfer the analogy between the class’ happiness and their personal happiness.

I then move to using numbers and assign a “happiness index” to the room, say 3. I would ask students how I might change the happiness in the room from a score of three to a score of five and record their suggestions numerically:

i.e. 3 + 2 = 5 or 3 – –2 = 5

I find this helps students to reason their way to an answer rather than just remembering rules (two negatives make a positive).

I’ve taught negative numbers several times since this lesson and I have just been looking at where I was from different perspectives. Occasionally I would use a power point. Sometimes coins to distinguish between happy and sad people. Sometimes I would just ask how students were feeling. The initial analogy works as it seems everyone understands that letting go of negative thoughts makes you feel better, and that one’s state of happiness results from a sort of balancing up of good thoughts and bad thoughts. What is also powerful is that it is easy to remember and retrace the thought process that leads to removing negativity.
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01 October 2012 10:28
I use 'The M Factor'
We play and score some songs between -5 and 5. I score the songs and use a negative score.
We add the totals, and then the total without me (as what do teachers know about pop music?!)
By the end of the session it's fairly obvious taking away my negative score increases the overall score.
By Maths123456
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18 November 2009 18:03
whoops apologies - you were complaining about "the rule" But any teachers out there who still say "2 negatives make a positive" read all of the above and get positive, please
By sallyb
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18 November 2009 18:00
As a teacher of post 16 can I also ask you to lose the "2 negatives make a positive" it leads to -3 -5 = 8 type of answers, (and lots of other inappropriate uses) Just stick to taking away a negative number gives you the positive feeling...
By sallyb
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02 November 2009 13:31
Lovely idea and memorabel.

I always call negative numbers, directed numbers and explain they change the operation. So we go bouncing up and down the number line remembering to change the order of the operation if we hit a negative number. It seems to work and I have one of my students from 10 years ago teaching this way in NY, where it nevers seems to have been considered before. I make a point of never saying 2 negatives makes a +, can't even utter it now!! Well done.
By leescholey
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