Re: [Phys-l] Any teaching tips

[John Denker <jsd@av8n.com>]

On 01/26/2011 08:05 PM, Rman Towndog wrote:
> I'm teaching Physics (Algebra Based), we are learning about kinematics in 1-D.  
> I have students that have trouble listing knowns and unknowns.  I tried to get 
> the students to learn the units (e.g. speed is m/s, etc), so they would know how 
> to do this step, but it's been largely unsuccessful.  Any tips?  

I don't understand the question, in the following ways:

1) I've never attached much importance to "knowns" versus "unknowns".
 That's because in real-world situations, especially if there is
 any kind of feedback involved, there is no clean dividing line
 between knowns and unknowns.  Depending on style, different people
 can choose different sets of "knowns" (or none at all) and solve
 problems equally well.

 Yeah, I know that at the intro level, textbook problems are cooked
 to look like they have definite "knowns" and definite "unknowns",
 but this is such an artificial game that I'm not interested.

 Also, to the extent that there are "knowns", there are billions
 of them, so we need to ask which of them are /relevant/, which
 is an entirely different question.  The question generally has
 no unique answer.

2) Units are important, but I cannot imagine how focusing on units
 helps with knowns-versus-unknowns, or vice versa.

Therefore, in light of (1) and (2), some tips:
 A) If the _only_ problem has to do with "knowns", I suggest you just 
  skip it and move on.  It's not worth worrying about.

 B) OTOH I suspect there are some actual problems afoot.  The problems,
  whatever they may be, will produce a long list of symptoms, not 
  confined to knowns-versus-unknowns, and before diagnosing the problems
  I would need to know a lot more about the symptoms.

  For example, in an algebra-based physics course, there will be some
  students who can't do algebra.  Can I assume you checked for that?

  There are a gazillion other basic checks that need to be made.
  Knowns-versus-unknowns is only one item on a very long list, if
  it's on the list at all.