Date: Aug 10, 1995 12:14 PM
Author: David Van Slyke
Subject: Re: nctm-l-digest V1 #119

> From: rex@bertha.cqu.edu.au (Rex Boggs)

> Date: Wed, 9 Aug 1995 19:48:40 +1000

> Subject: re: el fractions etc

[snip!]

> But what question can you pose where the necessary operation is

> dividing, say, 1/4 by 3/5? I used to think there weren't any such

> questions, until I read a good response last year (somewhere on the Net..)

>

> Think of division of fractions another way -

> first think of 3 divide 6 = 1/2 as meaning that 3 is 1/2 of 6. Also,

> 1/4 divide 2 = 1/8 means that 1/4 is 1/8 of 2, So 1/4 divide 3/5

> becomes ' 1/4 is what part of 3/5?' and the answer is that 1/4 is

> 5/12 of 3/5.

>

> I haven't come across anything better than that.

How about the following:

How many quarter-pound bags of rice would you need to buy in

order to have 5 1/2 pounds of rice?

(For a very thought provoking article on this subject, I recommend "The

Mathematical Understandings that Prospective Teachers Bring to Teacher

Education", by Deborah Loewenberg Ball, The Elementary School Journal,

Vol 90, No 4, Pg 449-466)

-DVS