Re: What Flows?

[palmer@sfu.ca (Leigh Palmer)]

Paul counters:

> I don't think anyone has suggested deliberately lying to students (at
> least, I hope not). My reading of this discussion has been more in
> terms of a recognition that a simple assertion of a fact without a
> context within which the student can see that it is a necessary one.

I thought I had given you a perfectly good context within which the
student *must* use the concepts correctly to get the correct answer.

> In other words, a student learns primarily (if not exclusively) by
> discovering that his/her current conceptions have failed in analyzing
> the current problem and then trying to replace them with more precise
> and useful conceptions. This is in fact exactly the thrust of the
> example you have given in which a hypothetical student confronts an
> inconsistency between two colloquially held ideas. THEN you have an
> opportunity to teach but before that confrontation occurs, most of
> the time you do not. It goes in one ear and out the other as you
> haven't got any phenomenon for your words to latch onto in the
> student's mind.

Since you are going to introduce the concepts anyway, what is to be
gained by introducing the wrong ones first? I think the answer is
that nothing is to be gained. The student will never understand the
resolution of that particular paradox (the adiabatic equilibrium of
the atmosphere) without the correct definition. Would you say "As the
air rises it loses thermal energy" or "its thermal energy decreases"?
Would you say "There is a flow of heat out of the air as it rises"!?
All of those are, I hope you will agree, very wrong. Please tell us
how you are going to reconcile this apparent contradiction using the
flawed concepts you claim are satisfactory for use by beginners.

Deriving the adiabatic lapse rate for a college class (this is a
second year topic here at SFU, by the way) is very satisfying. It is,
perhaps, something they had never wondered about before, even if they
had noticed the term "temperature inversion" in the TV weather news.
We've got to get them back to basics, and the most basic thing of all
is that physics describes Nature.

Leigh