Re: The conceptual change process (long)

["Donald E. Simanek" <dsimanek@eagle.lhup.edu>]

On Tue, 17 Feb 1998, William Beaty wrote:

> I do agree that a ban on the words "charged" and
> "discharged" leans too much towards the behavior of a Grammar-nazi.  But
> it still gives me the creeps to use them, knowing how I was misled myself,
> and gradually discovering more and more others who have this same
> "infection."  I'm not trying to force terminology on people in order to
> satisfy a pendantic streak in myself.  I'm trying to get them to stop
> teaching a misconception.

Bill has done teachers a great service by telling in detail how the usual
treatment of this concept and the language used, lead to misconceptions,
or incomplete conceptions. This happens more often than teachers are
willing to admit. Many teachers aren't even aware of any "problem" until
they ask "concept-challenging" questions on homework or exams. Too often
we ask only "safe" questions for which students may get the right answer
even with poorly formed concepts. This is how we can deceive ourselves
into thinking that (a) our teaching is good, (b) students are achieving,
(c) the teaching philosophy I'm using is the best one (be it conceptual,
mathematical, or whatever).

In science we say that every hopotheis, law, and theory must stand up to
rigorous testing against nature, especially against the kind of testing
designed to try to demonstrate that it is wrong.

But in the ed-biz, testing is usually designed to show that current
popular fad X is right, good, and better than anything else we've ever
tried. Seldom does anyone subject it to skeptical testing designed to
reveal its deficiencies. (Those who might want to don't get funded.) No
wonder the pendulum keeps swinging from one fad to another and back again.
We have built a system with guaranteed instability and guaranteed failure. 

So I advocate more "concept-challenging" testing. A concept is impotent if
it can't stand up against rigorous challenges. 

But back to the capacitors. My problem with them as a student wasn't
apparent. I could answer any of the questions about capacitors, but didn't
really *have* a concept of what was going on in them. I think I first
realized this when I encountered a concept-challenging question:

	A capacitor is charged with Q on one plate and -2Q on the other
	plate. The potential between the plates is V. What is the
	capacitance of the capacitor. What is the energy stored in the	
	capacitor? Explain your reasoning fully.

It made me think, for the first time, "What does *capacitance* really
*mean*?" Also, "What is the function and purpose of a capacitor?" The
question may not have a clear-cut answer, but it surely exposes the
inadequacy of one's concepts.

BTW, "is charged" can mean simply "has charges on its plates". It can also
mean "was given a particular set of charges on its plates". This can mean
that "Charge Q1 was put on one plate and charge Q2 was put on the other
plate (by whatever method you like)."

When we try to form concepts without math, or minimal math, we are left
with only words and pictures. Words are a blunt and slippery tool for
concept formation and pictures have the limitations of being only
two-dimensional representations of a 3d (or worse) world, and even more
limitations when they try to represent something which *can't even be
seen*". I think that this thread has very well illustrated the limitations
of words for concept formation.

	--Donald

......................................................................
Dr. Donald E. Simanek                            Office: 717-893-2079
Professor of Physics                                FAX: 717-893-2048
Lock Haven University, Lock Haven, PA. 17745
dsimanek@eagle.lhup.edu                 http://www.lhup.edu/~dsimanek
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