Re: College nowadays - What "should" students know?

[Hugh Logan <hlogan1@BELLSOUTH.NET>]

Doug Craigen wrote:

> >     But many HS courses (even those that are not A.P.) use college textbooks
> > and strive to cover a large chunk of them. What else are they doing besides
> > mirroring college courses?
>
> (One of these days I'll have mentioned here all the things I do for a
> living.)
> Last night I began tutoring another student - this one a girl in grade
> 10 physics (doesn't exist in most schools around here so I guess they've
> got a lot of freedom).  They are covering some interesting material
> which is not just trying to get a headstart on the next class (the basic
> complaint being echoed above).  Her big problem last night was with
> strobe questions.  A sample would be "a strobe light is flashing at a
> rate of 12 per second while a two blade fan turns at a rate of 5
> rev/second.  Describe what is observed and explain your reasoning."  I
> don't think I've ever seen such questions tackled in a physics class
> before, but on the other hand she says the entire class is completely
> baffled.

One of my first teaching experiences was with the second edition of _PSSC
Physics_.
This edition contained about ten introductory chapters. Besides in-depth
treatments of vectors and kinematics, there were chapters on topics like
measurement, scaling, and orders of magnitude. In particular there was a detailed
discussion of stroboscopes, with many problems and examples like the one referred
to in Doug's message. I recall a standardized multiple choice test with questions
on stroboscopes that accompanied the text. This seemed as much like an IQ test as
a physics test. The students related to things like the wagon wheel effect, but
the time needed to reach an understanding of stroboscopes was significant. The
PSSC course reinforced the understanding and application of stroboscopes with lab
exercises involving hand-held rotating disk stroboscopes with a variable number of
slits. One student counted the number of revolutions while his partner measured
the time interval, from which the number of "glimpses" per second could be
determined. Presumably flashes from a Xenon bulb
were too expensive to use. The PSSC lessons also served me well in college labs,
where,
for example, the frequency of a vibrating string had to be determined
strobiscopically-- not mistaking the actual frequency for a multiple or
sub-multiple thereof.

Later editions of _PSSC Physics_ omitted most of the introductory topics, except
those
on vectors and kinematics. It was just too much for one course. As a beginning
teacher, I wondered if a comparable number of chapters on topics that I thought of
as physics (like electricity and magnetism) should be omitted. I have always felt
that much of this introductory material was common to sciences other than physics
-- as much matters of scientific literacy as of physics itself. Rather than
wasting the efforts of the distinguished physicists that contributed to this
material, I have wondered if much of it couldn't be distributed across the science
curriculum -- physical science, chemistry, and even biology (as in the case of
scaling, for example),  not to mention physics. Perhaps this has been done to some
extent.

Hugh Logan