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Re: Fluff for the day



-----Original Message-----
From: John S. Denker [mailto:jsd@MONMOUTH.COM]
Sent: Friday, May 04, 2001 11:54 AM
To: PHYS-L@lists.nau.edu
Subject: Re: Fluff for the day

For some strange odd reason, I feel I need to defend myself.

Neat question, I think I have one of my final exam
questions, now! Thanks!

IMHO the final exam is _not_ a suitable setting for a
question like this,
where we expect most people to get it wrong --- because there is no
opportunity to follow up. Without follow-up, such a question serves
neither purpose 1 (learning by doing) nor purpose 2 (evaluation) nor
purpose 3 (foundation-laying).

I don't necessarily expect most people to get it wrong. It certainly is
well within the realm of the homework problems assigned and previous hourly
test problems that my students have seen in the pertinent class. It clearly
isn't computationally cumbersome or time consuming, it does require one to
think in a non-regurgitive manner, however.

If I decide to ask the question, and if I get a student who answers in the
"near logical" fashion you postulated, that student will get near-to-full
credit.

I fully expect that it will satisfy purpose 2, which is why I think it is a
neat problem. It will also partially serve purpose (4) I mention below.

In very very minor ways it can also satisfy your purposes (1) and (2), for
*some* students; namely ones who come and look at the final exam after the
fact and thereby gain follow-up and for those who take a later more advanced
course and will obtain some follow-up there.

In real life (unlike an exam), if a question doesn't make
sense, you can
usually ask for clarification.

Actually during all of my exams my students can easily ask for
clarification, are encouraged to do so, and in fact do so. Which means that
during my exams its easier to get clarification than is often the case in
"real life".


And as an aside, which isn't irrelevent to the topic

What is the purpose of posing a problem to students? IMHO:
1) The primary purpose is that the students should learn
something by
working he problem.
2) The secondary purpose is that the teacher should learn something
about the students' progress.
3) On rare occasions the purpose is to lay the foundation
for a later
discussion.

I'm a believer in the philosophy of "that which is worth teaching is worth
testing over". Anything else provides a clear signal to students that
certain topics of discussion can be safely tuned-out.

Consequently I'd add a 4th reason to your excellent list.

4) A *tertiary* purpose is to provide a clear signal and guide to the
students as to what material and level of difficulty and computational skill
are important and appropriate to this particular course of study.

In consideration of this, I think it is entirely reasonable to assign *some*
problems that you might expect everybody to answer correctly or incorrectly
*as long as* you really think the question accurately reflects in a
legitimate fashion aspects of the course that were worth teaching and at an
appropriate level.

This not only signals to the class that this was/is material that is
important (of course on a final exam this only becomes pertinent to students
taking a follow-up course), but it also signals to future students of the
course that this is material is worthy of study and attention, as it may
appear on a test that you have to take.

Joel Rauber

PS

I think a good example of Denker's purpose (3) is the classic electrostatics
problem of a uniform spherical distribution of charge with an off-center
cavity.