Teaching Fractions of an Inch

Date: 7/9/96 at 11:51:28
From: Anonymous
Subject: How to teach the Inch

Dear Dr. Math,
I am a special needs teacher at the Addison Career Development Center 
in Middlebury, Vt. In many of the trades, but especially in Building 
Trades, we find students ages 16-18 who can't do linear measurements.  
Do you have any suggestions on how to best teach the "inch." We have 
tried a few texts but haven't been successful. Any books, handouts, 
etc.that you have found successful?

Sincerely,
Kay Doolan

Date: 7/9/96 at 17:24:25
From: Doctor Ceeks
Subject: Re: How to Teach the Inch

Hi,

My first reaction is that the concept of distance seems to be 
something best taught if the notion is made visceral in some way.  
These concepts are associated directly with the real world, after all, 
and to have people learn them from books seems a little bit strange.  
I know I certainly did not learn these concepts from books, but from 
contextual usage in real life situations.

I've never tried to teach special needs students, so I don't know
what works best, but here is a suggestion of what I have in mind:

Have the students build a baseball diamond. Inevitably, they will
wonder how far apart to put the bases and need to think of some way
of describing this. It doesn't matter whether they use inches at 
first. If they use pacing, or feet, or yards, whatever. It's the first 
thing to understand that distance is something which can be quantized 
and 30 yards or 90 feet or whatever is the same whether you're in 
Brooklyn or Honolulu.

Alternatively, have them compete in a long jump competition...or
compete in a limbo competition...they will have to think of someway
of remember (recording) the height of the limbo bar for the next
competition.  Again, it doesn't matter if they use their own standard
of measurement because the important concept of distance is its
quantizability and its invariance.

Once distance is understood, the inch can be introduced as a standard
unit used by millions of people.  The use of the inch has less to do 
with distance than with the problem of communication.

-Doctor Ceeks,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   

Date: 7/11/96 at 12:37:34
From: Kay Doolan
Subject: Re: How to Teach the Inch

Dear Dr. Math,
Thanks for the answer. I am taking a computer course and yours is the
first reply I have ever gotten through E-mail. This is fun! 
However, I guess I didn't ask a very clear question. How do you teach 
a group of Building Trades students to measure to 1/16ths?  How do you 
get them to read 1/2, 1/4, 1/8, etc?

Thanks,
Kay D.

Date: 7/11/96 at 14:8:52
From: Doctor Ceeks
Subject: Re: How to Teach the Inch

Hi,

This is a very difficult question to answer without being directly
involved with the students.  There are so many facets to understanding
fractional measurements that it is impossible to guess what each 
person is having trouble with (is it fractions themselves? Or could it 
be the problem that most things are not measurable in simple 
fractions? Or could it be technique in actually carrying out the 
measurement? etc)

However, there are many concrete objects (wood planks, screw size,
nail length, etc.) which demand measurements accurate to the 16th 
inch. Perhaps if you make them try to build something which demands 
such accuracy, they will be forced to understand the importance of
measuring to the 16th inch.

If you can describe in more detail what is happening with the
students, Dr. Math can probably be more helpful.

-Doctor Ceeks,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/