Re: [Phys-L] ill-posed questions; was: potatoes

[John Denker <jsd@av8n.com>]

On 01/13/2015 10:38 AM, Dan Beeker e:
> I must throw in my two bits worth. I have encountered many such
> questions as a student and as an instructor. I generally found them
> to be confusing and frustrating because 1. The instructor didn't just
> come out and say the question is meant to be a discussion question
> and 2. The instructor did not say there may not be an exact, i.e.
> right or wrong answer. This put me in a position of wondering is
> there an acceptable answer? Then I would ask the teacher - what is
> the correct answer with a response of "I don't know." or "I can't
> tell you."  I would spend so much time wondering what an appropriate
> response to the question would be I would miss important parts of the
> lesson that followed. I suppose one should always be on guard for ill
> posed or open ended questions questions but somewhere along the line
> it is really helpful to the student to be given some guidance as to a
> correct/i.e. reasonable response. There's nothing wrong with saying
> it is an ill posed question from the git go.

Amen, brother.

This is a super-important thing to discuss in this forum.

> If a student is constantly wondering "is this a discussion question"
> or "is it learn a rote task question" the student will often be
> focusing on the wrong aspect of the material being presented. I see
> it all the time in teaching our lab courses. In short, be careful how
> you present such questions as well as be explicit in explaining your
> answers (or lack thereof). Confusion is not always the student's
> fault.

Students are not born knowing how to handle ill-posed
questions.  It is an acquired skill.  It has to be taught.

Everybody says that the most valuable outcome of the
physics course is the reasoning skills (not the low-
level physics factoids) -- but all too often the reasoning
skills are taught poorly or not at all.

The International Baccalaureate curriculum has a separate 
course on Theory of Knowledge (ToK) ... which is IMHO a
tremendous mistake.  Reasoning is not something you can
sprinkle on afterwards, like powdered sugar on a donut;
it has to be baked in, like the carrots in carrot cake.
This starts in first grade, with basic principles such
as CHECK THE WORK, and learning to ask "Do you think
that big cat is telling the truth?"

Reasoning should be baked into every course, not just
physics, but especially physics.  Somehow the physics 
teacher is expected to teach reasoning plus remedial
math plus technical writing plus all the physics.  It's
not fair, but we're stuck with it.

On this list, lots of people know what they're doing.
When they see an ill-posed problem, they recognize it
as such, and immediately find ways to transmute it into
the question(s) that /should have been asked/.
  https://www.av8n.com/physics/ill-posed.htm

However, all evidence indicates that people who know
how to handle (or even recognize) ill-posed questions
are the exception not the rule.

It would be nifty if the book explained how to handle
ill-posed questions, but it doesn't.  It's fine to have
some ill-posed questions in the book; that's not the
problem.  My point is that the questions are not handled
properly.  I don't know what is worse, the paucity of 
good analyses or the prevalence of bad analyses.


On 01/13/2015 12:30 PM, trappe@physics.utexas.edu wrote:
> > Our analysis  is so sorely lacking in data points that we would flunk
> > our students for submitting this discussion as their lab experiment?

And yet the analysis here is far more nuanced and far
more fact-based than the "answer" given by Hewitt.

Hewitt addresses the fact that the potato is /served/
in foil, but spectacularly fails to consider other 
well-known data, such as the fact that the potato (if
wrapped at all) was wrapped /before/ cooking not after.

  This violates the ultra-basic rule:  Check your
  theory against all the available data.

What's worse is that except for people on this list,
it is hard to find evidence that anybody even notices
the bogus answers to questions such as "Why do forces 
always occur in pairs" or "Why wrap the potatoes" or 
"When does light act like a wave? Like a particle?"
By and large folks seem to be perfectly happy learn 
by rote a bunch of mindless, nonsensical answers to 
such questions.

Writing a textbook is a hard job.  Writing a decent
textbook is an even harder job.  That does not however
mean it is OK to do it badly.  At some point it becomes
a management issue:  Allocate enough resources to get
the job done properly.

There are many levels of reasoning ability.  I'm not
suggesting that introductory textbooks should be
written at the level of a tenth-degree black belt.
I am however saying that the reasoning level is
currently very low, and it would be easy to move
up several levels.