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Re: Spiral Approach within general physics



Another reason for revisiting relates to the alternative mental models
that are held so firmly by all of us, but in this case by our students.

All to frequently I find students tend to forget experiences that
confront their conceptions. If I create such an activity and then ask
after a month or so what happened last month when we did whatever it
was, many will recall what they expected to happen, rather than what
actually did happen. This is especially problematic when the recalled
experience is the primary data for supporting the new mental model I am
trying to use. To counter this, I try to find ways to revisit the
experience. It is also a good way to sell students on the value of
keeping a journal, since the written record they have shows what
actually did happen, and it is not what they remembered.

cheers,

joe

On Wed, 24 Jul
2002, Steve Clark wrote:

I teach at the high school level and I know from experience (21 years now)
that it is vitally important that you revisit topics throughout the year.
The most important reason (in my opinion) is because we have trained kids to
think about school as passing a series of tests rather than learning
material. The spiral approach discourages that approach because they have to
continue to demonstrate skills that were previously tested. Furthermore, it
shows the kids that the concepts link together and are internally consistant
- which they don't seem to get from chemistry and biology. Finally, they
actually get good at mechanics by the end of the year. And many report back
to me that they think about the concepts outside of class (often to their
dismay but my delight).

I've taken an approach like the one Vern suggests here for several years. t
has always puzzled me why the traditional texts discuss projectiles with one
dimensional kinematics. It is quite a stretch to think that a kid will
intuitively understand that an object falling vertically has the same
vertical acceleration as one projected horizontally. Without a foundation in
second law, it doesn't seem reasonable to most. Even after second law they
struggle, but at least I can demonstrate why it should be so.

Just this past year I did work before circular motion and liked it. It could
discuss why the speed is constant in uniform circular motion and why
Kepler's 2nd law is true. What a deligt it is to me to be able to give
explanations based on student understandings. And it is so much more
pleasant than watching students struggle with ideas that I know are out of
place.

Yes, think about physics as a mess of connections that can be (should be)
traveled in several directions during the course. The kids will appreciate
it.

--
Steve Clark, Ph.D.
Physics Instructor
Starr's Mill High School
193 Panther Path
Fayetteville, Georgia 30215
(770) 486-2710
clark.stephen@fcboe.org

The box said "Requires Windows 95 or better,"
so I bought a Macintosh.

From: Vern Lindberg <vwlsps@RITVAX.ISC.RIT.EDU>
Reply-To: "phys-l@lists.nau.edu: Forum for Physics
Educators"<PHYS-L@lists.nau.edu>
Date: Wed, 24 Jul 2002 09:53:59 -0700
To: PHYS-L@lists.nau.edu
Subject: Re: Spiral Approach within general physics

During various discussions, the idea of a spiral approach to education has
espoused several times by various members. ...



I haven't thought this through completely, but I am liking it more and more
as I think about it.
Has anyone tried something like this?
Are there major pitfalls I am overlooking?
Would it be an improvement over the "standard" approach?

I have tried the following, using a traditional text such as
Halliday, Resnick, Walker (HRW).

1. One-dimensional kinematics
2. Vectors
3. Newton's Laws constraining motion to one dimension (individual
forces can be any direction)
4. Work and energy and applications NOT including circular motion
5. Momentum and Impulse, 1D and 2D
6. Two-dimensional kinematics, constant acceleration and circular
including non-uniform circular
7. Newton's Laws and Energy applied to circular motion
8. Continuing on into the rest of mechanics (we are on a quarter
system so this means General Law of gravity and Static Equilibrium.

Why I like it:
1. Quickly in the quarter cover the basics of mechanics: kinematics,
Newton's Laws, Energy, Momentum

2. Spiral back to revisit each of these topics

3. Circular motion as an application shows how kinematics, dynamics
and energy conservation work together.

What I would change:

I have used the Cummings et al rewrite of HRW along PER principles. I
really like the fact that they did impulse-momentum before
work-energy. So I would reverse 4. and 5. in my above list.

I can't claim any careful study about whether this order is an
improvement, but I am confident that it is as good as the traditional
order.


Joseph J. Bellina, Jr. 574-284-4662
Associate Professor of Physics
Saint Mary's College
Notre Dame, IN 46556