Q&A #750


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From: Gail (for Teacher2Teacher Service)
Date: Nov 08, 1998 at 16:24:55
Subject: Re: Multiplication

Hi, Crystal --

I think one reason it may be difficult for some students that age to learn
the algorithm we present to them is that they really don't understand what it
is they are doing when they multiply the two numbers.  If they haven't a good
idea of what the answer should be (i.e., a reasonable estimate of some
sort) they probably don't have a good idea of what is happening with smaller
multiplication problems either.  When I present multiplying of these sorts of
numbers to my upper elementary students, I give them concrete examples of
what we are doing.  We actually draw out the multiplication using rectangular

For example, for the problem 17 X 23, one side of the rectangle measures 23
units, and the other side measures 17 units.  Inside that large rectangle we
find there are four smaller rectangles, a 3 X 7 rectangle, a 3 X 20
rectangle, a 10 X 3 rectangle, and a 10 X 20 rectangle.  We look at all four,
and determine where they are shown in the traditional algorithm.  Some
students continue drawing the rectangles for quite some time.  They haven't
made the concrete - to- abstract connection yet.  Others discard the strategy
almost immediately, because they have a mental image of what is happening.

 -Gail, for the Teacher2Teacher service

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