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[Phys-L] Re: Human Error?



Vickie's description of students' lack of understanding of the inner
workings of devices reminds me of the Isaac Asimov short story, "The
Feeling of Power", in which an engineer rediscovers how to do arithmetic
by hand. Everyone had been so absolutely dependent on computers to do all
calculations that they had all forgotten that it was even possible to do
arithmetic without a computer. I deal with only the best students in math
and science from several area high schools, so I don't see as much
ignorance of internal mechanisms as Vickie, and presumably many other high
school physics teachers, see. I do get a few every year, however.

Daniel Crowe
Oklahoma School of Science and Mathematics
Ardmore Regional Center
dcrowe@sotc.org

On Sun, 1 May 2005 13:52:25 -0500, Frohne, Vickie <VFrohne@BEN.EDU> wrote:

I'd like to second some of this. In introductory physics, we're usually
asking the students to replicate some well-known result such as the
acceleration of a ball down an inclined plane. There is nothing new or
exciting to be learned here, and the students know it. Therefore the best
they can do is to try to get the accepted value. Usually, their
experimental technique is too poor for this to occur. We can, however,
introduce the concept of an "error bar" and what it means to "agree"
experimentally. Besides being totally unfamiliar with the concept of
quantitative error analysis, most students are amazed to hear that the
accepted value has error, too. It takes some effort to steer students
away from the vague and automatic "human error" toward a more thoughtful,
insightful, and quantitative approach.

One way to do this is to find some variation on the standard experiment
for which there is no accepted value - finding the spring constant of
stretchy toy snakes, for example. Students must be taught what to do when
there is no "accepted" value. They just don't know how to cope with
that. The have never experienced the kind of experimenting that's done to
answer a question. (Which, of course, is the whole point of doing
experiments!)

Part of the difficulty is that many students have very little concept
of "mechanism." If you ask 'em how it works, they say, "push that
button." In their common experience, either something works perfectly or
it doesn't. If it can't be restored to functionality by recharging or
replacing the battery, it gets thrown out and replaced. Nothing can be
repaired. Everything is purchased - nothing is made at home. Even if you
know what's wrong, you can't do much about it. So most people never
bother to find out what's wrong with a malfunctioning device - they just
replace it. Students literally have no clue where stuff comes from or
what makes it work. Therefore the concept of digging deeper into an
experiment in order to figure out why it's not working perfectly is also
foriegn. Even my calculus-based students didn't know that the "green
thing" (the circuit board) contains resistors and capacitors and is
responsible for the functioning of their computers and cell phones. So
we're fighting an uphill battle, everyone.

Vickie Frohne
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