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Re: [Phys-l] Misconceptions (was: caloric)



Thanks John Clement, you saved me some typing.

joe
Joseph J. Bellina, Jr. Ph.D.
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556

On Apr 24, 2006, at 7:56 PM, John Clement wrote:

jbellina wrote:
On the other hand, could it be that those same students think of
energy as caloric? If that is the case would it be useful to name
the misconception so as to deal with it?

In my considered opinion, no, that usually isn't helpful, and
certainly isn't required, for the following reasons:

1) I can perfectly well _describe_ the most-common heat misconception
using the words "thermal energy is (allegedly) separately conserved,
separately from other forms of energy". Giving the concept a name
just adds one step of indirection. Using the long-winded form takes
only a few milliseconds; I can afford that.

I can dismiss this misconception using only a few additional words:
"Push your hands together and rub vigorously, like /this/."


No, You think you can dismiss the misconception by this method. However
research shows that they are deeply imbedded and such simple methods do not
in general work.


2) An _accurate_ description of caloric theory would be more complicated,
far more complicated than the subject deserves, and I hate to give out
inaccurate information, even about long-dead theories. Lying about
history is hardly preferable to lying about anything else. It gives a
false impression of the scientific process.

3) For some students, giving the concept a name confers on it an
unhelpful level of seeming-dignity and seeming-importance.

Actually there is evidence that taking a historical point of view, where
various misconceptions are named, actually works. There was an article in
AJP in an optics course (I think) where students debated various historical
points of view. The result was gain in understanding far above that in
conventional courses where only the correct results were exposed.


4) In general, I find dealing with misconceptions to be a very
tricky business. It is all too easy to inadvertently teach the
students how to _make_ mistakes ... instead of teaching them how to
*avoid* mistakes.

Also, it can be proved on theoretical grounds that for every correct
conception, there is an infinite number of misconceptions. One cannot
even dream of covering them all, or even naming them all.

Actually Piaget showed that when you ask a student a question the wrong
answers cluster around a small number of answers. So the misconceptions
actually form a small number which is not infinite. This is the basis of
the FCI which only uses the common misconceptions as distractors. The
combinations of misconceptions may be very large.


Discussing misconceptions one by one is like hunting bacteria with a
sniper rifle. It's not efficient, and there is too much collateral
damage.

Actually there are some that need to be hunted, but when a teacher talks
about them, they are usually not killed.


Some data on this: In a talk I gave last week, there were 40 slides.
a) One slide dealt with two misconceptions.
b) Half of another slide contrasted one of those misconceptions with
the corresponding correct conception
c) Another slide dealt with four more misconceptions.


There are plenty of other relevant misconceptions that I didn't even
mention. Instead, the key slide (c) was little matrix with observed
facts as columns and theories as rows, showing that even a few facts
suffice to instantly discredit a wide range of misconceptions.

This is the "antibiotic" approach to killing misconceptions: You've
got to kill them _many at a time_, not one at a time.

5) I will sheepishly admit that I sometimes use misconceptions for shock
value, usually when talking to an audience of know-it-alls (*not* naive
students). I bait my hook by putting up slide "A" full of well-"known"
misconceptions, and when they are all comfortably agreeing with the
slide "A" -- "yeah, yeah, we know all this" -- I jerk them awake with
slide "B" that flatly contradicts slide "A". I like this, because
it teaches them to be skeptical, i.e. not to agree with everything I
say (or anybody else says). It also establishes my cred as somebody who
knows nontrivial things about the subject.

This technique is *not* appropriate in front of naive students. The
disadvantages far outweigh any possible advantages. As James Randi
likes
to say, magic works by confounding our expectations. You can't do
certain
types of magic in front of young kids, because they don't have the
relevant
expectations.

_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l


_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l