Re: TA Problems

[John Denker <jsd@AV8N.COM>]

Quoting Gary Turner <turner@MORNINGSIDE.EDU>:
> .... general physics class (physics,
> mathematics, engineering, chemistry, biology, comp sci, pre-med).

A mixed audience is always a big source of headaches.

> One of
> the problems I face is the MCAT requirement on the content that must be
> covered.
>
> Does anyone have any experience of why the MCAT has physics on there at
> all?  It does not seem likely that our future doctors will need to know
> about blocks sliding down ramps!

Obviously I don't speak for MCAT ... but I think there's a
way of looking at this where the MCAT angle mostly drops
out anyway.

1) Let's start by looking at some bits of the bigger picture:
 -- simple machines:  ramps (aka wedges) are one example of
    a simple machine.  Pulleys are another.  Levers are another.
    The goal is to get students to the point where they see
    this as a package:  if you've seen one simple machine
    you've seen 'em all.
 -- There is an even bigger package involving forces, resolution
    of forces into components ... and the great conservation laws
    (energy, momentum, etc.).  Everybody, even pre-meds, ought
    to know this IMHO.


2) Dropping down to a much lower level, we probably all agree
that blocks on ramps (per se) are dead boring.  That technology
was big with the pyramid-builders but has since been largely
superseded.  Carts (as opposed to blocks) on ramps can be sold
as being representative of
 -- skiers on ramps
 -- cars going downhill or uphill
 -- airplanes in a climb or descent
 -- etc.

Last but not least, if you're trying to sell the course to a
bunch of pre-meds, you can swap one simple machine for another.
The usual ramp (going down from east to west) with a cart
pulled by a string can be swapped out and replaced
by a lever [bone] with a pivot [joint] high in the west,
pulled by a string [tendon].  The big issues (energy,
resolution of forces, etc.) are the same.

I would do *some* problems with ramps and *some* problems
with bones/joints/tendons ... all the while driving home
the idea that if you've seen one simple machine you've
seen 'em all.

> I had convinced myself that it was about
> problem-solving skills, but the MCAT questions are all plug-and-chug rote
> memorization.

That's a problem.  No full solution is available, but by way
of *partial* solutions, some things you can say to students
include:
  1) There are dozens of physics principles and thousands of
applications.  Do you want to learn thousands of special cases
one by one, or do you want to learn the principles?  At some
point thinking becomes easier than cramming.
  2) Right now you're fixated on getting *into* med school.
But how are you going to get *through* med school if you
haven't learned how to think?
  3) For that matter, what about *after* med school?  What
if some patient walks in with a rotator-cuff injury and you
haven't got a clue how a rotator cuff works?  (Hint: *my*
GP knows how a rotator cuff works, and can explain it in
basic physics terms.)
  4) Physics (at least the physics we're doing in this course)
is *simple* compared to biology/chemistry/biochemistry/medicine.
It's like learning to swim while the water is still shallow.
I guarantee you that deeper water is coming, and if you wait
until the water is over your head and *then* try to learn the
basic skills, you'll be sorry.
  5) Combining ideas from (1) and (3), not all the special
cases are known.  Eventually in your practice you will be
faced with things you cannot possibly have crammed for.  So
you'll just have to *figure it out*.  There are some things
that you ought to learn for the MCAT, but there other things
you should learn just for your own self-respect ... or if
that isn't enough, you should learn to think out of respect
for your patients.