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Re: [Phys-l] God as an explanation (WAS: Darwinism underattack?andthephysicsclassroom)



Hi Hugh-
When a teacher says, "I taught...", my reflexive reacttion is, "What did the students get?" You answer this, in part, when you say,

"I never asked them to derive any equation that involved more than
just simple algebraic manipulation, but they always got to the point
where they could take the work on to problem solving, knowing that it
had a firm foundation, and wasn't just another formula thrown at them
by their teacher."
_______________________________
But, to what extent were the students able to reproduce what you "taught", and to what extent did you challenge their ability to do so?
Regards,
Jack




On Fri, 1 Aug 2008, Hugh Haskell wrote:

At 17:28 -0500 8/1/08, David Whitbeck wrote:

Without calculus students can't even explore the relationship
between momentum and force. I certainly don't advocate any such
derivation or even mentioning it in an algebra based course. And in
a calculus based course, stating the connection and illustrating it
would be more appropriate than trying to derive it. Anyway unless
it's very short and sweet, imho derivations don't belong in
introductory physics. Students at that level don't really have a
good internal ranking of basic eqns and concepts vs derived results.

I think I disagree with most of this paragraph. Students can explore
the relationship between momentum and force without using calculus. I
taught my introductory HS students for several years, starting with
momentum, and using that to "derive" (quotes meaning that the
derivation was mostly non-rigorous) the idea of force as being what
causes momentum to change. In fact, we started with momentum
conservation as an empirically-discovered principle, and from that
beginning found all three of Newton's Laws. This can be done
rigorously, using calculus, but calculus isn't necessary to give the
students an appreciation of how the two ideas are related. This was
in an algebra-based course without even using trig. All the physics
was one-dimensional, so we didn't have to worry about vectors or the
complications they entail.

And I believe that derivations that the students can follow are
useful in an intro course, provided they are used sparingly, and done
for the purpose of showing them that the results are derivable and
are not something that just came from whole cloth (except, of course,
where they *do* come from whole cloth--i.e., experiment).

I never asked them to derive any equation that involved more than
just simple algebraic manipulation, but they always got to the point
where they could take the work on to problem solving, knowing that it
had a firm foundation, and wasn't just another formula thrown at them
by their teacher.

The object of an introductory science course is to get them to
understand the old saw that "science is no more a collection of facts
than a pile of stones is a house." If they don't know that what they
are doing when they are solving a problem is based on
well-established fundamental principles (where they really are), then
they will never understand the above metaphor. It isn't necessary
that they be able to understand the chain of reasoning or be able to
reproduce the development at this early stage--it is enough that they
know it exists, and that they can understand it with further study if
they feel the need. Unless they understand that, they will have no
idea of what science is about, and we will have wasted our time with
them.

Hugh


--
"Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley