Re: [Phys-l] Cramster et al.

[John Denker <jsd@av8n.com>]

On 05/08/2010 07:59 AM, David Craig wrote:
> I've seen a smattering of it in the past, but this year, the
> existence of services like cramster.com et al. really hit my
> upper-level courses in force.   Seems they have pretty thorough
> coverage of most popular texts.   (Even for books that aren't
> available at cramster, a quick google search turned up downloads of
> the solutions manuals for every single quantum mechanics text I'm
> contemplating using next Fall.)

This problem has been around for several decades that I 
know of, and presumably much longer.  Not the cramster 
part, but the "et al" part, which is as bad, or worse.

I distinctly remember the "intermediate quantum mechanics"
course from my grad-student days.  It turns out that there
are only a very limited number of intermediate-level QM 
problems in existence ... and every problem that was assigned 
as homework in our class could be found in the library as 
a worked example, if you looked through enough references.  
Some of my classmates were real whizzes and looking up 
such things.  I had to wonder whether they wanted to grow
up to be physicists or librarians.  Conversely, they thought 
I was an idiot for working things out, when I could just 
look them up.

The next year, a couple of these guys were standing in
the hall, in front of a big chalkboard.  They needed 
to calculate something so they could get on with their
research.  This was not a made-up homework/busywork
problem;  this was something they reeeally wanted to
know.  They didn't know how to do the calculation.
They didn't even know how to get started.  I overheard 
them.  I walked over, picked up a piece of chalk, wrote 
out the first few steps of the calculation and explained
how to do the rest.

They gaped.  They gasped.  They turned red.  They could 
not imagine how it was possible for the village idiot 
to solve a problem that they couldn't.  I explained that
the physics was similar to one of the homework problems
we had been given the previous year.  They asked, "And
you remember that $#!+?"

====================

The problem is not limited any particular text or any
particular course ... and never has been.  The only
thing worse than cramster is the situation where *some* 
students have access to previous years' problems courtesy 
of friends, siblings, and/or files kept in fraternity 
houses ... while other students do not.  That's grossly 
inequitable.  At least cramster is open to all.

Also, the problem is not limited to homework.  It also
affects cramming for tests, if you are ever tempted to 
recycle test questions from previous years.

> It's a bummer.   Either I go to writing all the problems myself
> (maybe not a bad idea in principle, but a MASSIVE time sink), or to
> choosing books just for their obscurity, or to devaluing homework and
> just giving a bunch of tests.    The latter doesn't really seem much
> of an option .. I don't generally find students will do anything that
> isn't actually required, no matter how much they "ought" to.   They
> just wait until the tests to realize they don't understand how to do
> it.

Well, devaluing the homework is not a time sink.  It saves
you time, because you don't have to grade the HW or even 
look at it, except if/when you choose to.

> They
> just wait until the tests to realize they don't understand how to do
> it.

So minimize the wait.  Give a couple of tests very early 
in the semester, tests that cover the same _principles_ as
the homework, so that anybody who _understood_  the homework
does well on the test, and anybody who skipped it or just
mindlessly copied it gets clobbered.  Explain exactly what
you are doing and why.  Explain it on the first day, and
explain it again and again, so nobody is surprised.

This has multiple advantages.  
 -- It reduces your workload.
 -- It gets the students into the habit of doing what they 
  "ought to" do, and doing it for more-or-less the right 
  reasons.  This is IMHO super-important.  I reckon school
  should teach students how to function in the real world.
  In the real world, they won't have somebody standing
  over them to make sure they do what they "ought to" do
  at every moment.  To put it bluntly, they need to learn
  good study habits, and they need to learn to act like 
  adults.  At one extreme, you shouldn't assume they already 
  know how to do this ... but at the other extreme you 
  shouldn't assume they can't do this.  You should push 
  them in that direction.

The tests don't need to cover every homework problem, just a 
sampling thereof.  This is called "statistical enforcement".
The same principle is familiar in other situations, e.g.
traffic law enforcement.  The cops don't need to catch every 
speeder every time; they just need to catch enough of them 
to create a deterrent.

===

The idea of ungraded homework is not original or heretical.
It is how I was taught, at the post-high-school level, with
isolated exceptions.  I remember one college course where 
the homework was heavily graded, but that course was considered 
a bit weird.