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Q&A #4952


Decomposition in math subtraction

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From: Gail (for Teacher2Teacher Service)
Date: Oct 30, 2000 at 23:09:44
Subject: Re: Decomposition in maths subtraction

Dear Margaret, I am glad the explanation helped. What I meant by shorthand was that we don't usually write out the place values for numbers. Instead, we let the place they are in tell that. So, where we would ordinarily write 359 I wrote out 3 hundreds 5 tens 9 ones. We definitely wouldn't want to continue to use this method of writing out the place values in words, because it takes a long time, and isn't really as easy to work with. Would we want to switch back and forth between the two methods? Well, if a child is having trouble with the way we are trying to solve a problem, sometimes it is beneficial to back up and show some of the underlying meanings (which is what we are doing if we write the number words out), and then try to move back into something more abstract. If it is still confusing, we may have to back up again. As for confusing children, I think they are much more adaptable than we give them credit for. They really need to recognize that there are multiple ways to solve problems, and that there are many ways to write amounts... for example, the number we were using before, 359, can be considered as 359 ones, or 35 tens and 9 ones, or 3 hundreds and 59 ones, or 3 hundreds 5 tens and 9 ones. It is all dependent upon which of those ways of looking at that amount is most helpful to us at the moment. Helping children see multiple ways is a way of empowering them to be problem solvers. (now I shall step back down off my soapbox, before it tips me onto my ear! :-) -Gail, for the T2T service Thanks for visiting our on-line community. Visit Teacher2Teacher again at http://mathforum.com/t2t/

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