From: "JACK L. URETSKY (C)1998; HEP DIVISION, ARGONNE NATIONAL LAB ARGONNE, IL 60439" <JLU@hep.anl.gov>
Date: Sun, 14 Jun 1998 8:42:51 -0500
Hi all-
In response to:
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If a student picks the wrong equation, give them a zero and leave it at
that. I _have_ given a mark in cases where the student did this, got an
unreasonable answer, but was able to explain why (e.g. "This wavelength
can't be right since the visible spectrum ranges from 400-700 nm"). In this
case, the student is thinking physics, just not enough to pick the right
equation.
Mike
Michael Porter
Colonel By Secondary School
Gloucester, Ontario Canada
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I have encountered students who have been taught that the way to
solve physics problems is by the "what equation do I use?" approach. I don't
think that this approach has much to do with learning physics. Such an
approach does, however, encourage the student to quickly absorb enough technique
to "get through" the course - and promptly forget the material. Such students
seem to be lost when they are asked to explain the principles involved in the
problems under discussion.
An example of a problem where such a student would be totally lost
is the following (closed book, clear desks, no cards with formulas):
A person throws a ball into the air and then catches it. Sketch
the ball in 5 positions: as it is about to leave the hand,
just after it has left the hand, at the top of its trajectory,
just before being caught, and as it is being caught. In each position,
show by arrows the velocity and acceleration of the ball.
This is the kind of problem that students will get mostly right or
mostly wrong. There is no need for fine discrimination in the grading.
Old AP exams are a fine source of well-thought-out problems and
multiple choice questions that distinguish between the thinking student
and the student who just worries about "what formula do I use."
Regards,
Jack
"I scored the next great triumph for science myself,
to wit, how the milk gets into the cow. Both of us
had marveled over that mystery a long time. We had
followed the cows around for years - that is, in the
daytime - but had never caught them drinking fluid of
that color."
Mark Twain, Extract from Eve's
Autobiography