From: Treg <thompst@axp.calumet.purdue.edu>
To: Teacher2Teacher Public Discussion
Date: 1999062715:32:25
Subject: Re: Integers Chips

	I also use the integer chips.  I've found variations of the idea on
the web.  Most recently this one
http://tqd.advanced.org/2897/integer.htm which uses positive and
negatively charged particles as an example.

Perhaps its taken for granted, but one of the most useful aspects of
the chips seems to be left out of the articles i've seen.  How to show
subtraction of a negative is the same as adding the positive.

For example, to show 2-(-2)=4.

This is easy to show with chips by adding in extra chips that sum up
to zero.  We show +2, by using more than just two plus chips.  You can
show 2 by having two plus chips, along with any combination of equally
matched pos and neg chips.  

Show 2 as,  +,+,-,+,-,+,-,+  (the extra chips add to zero)
now, take away 2 minus chips (2 - (-2))

you have +,+,+,+,-,+ which has a value of 4.

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