Re: Am I teaching what I should in HS physics?

[John Clement <clement@HAL-PC.ORG>]

I think that Tina has just seconded my opinion that first year college
students can have exactly the same problems as HS students.  All of these
problems have to be attacked simultaneously.  However, the problem that
students do not know what formula to use even when told, is really a problem
with conventional instruction.

Conventional problem solving as put forth in many books is explained as
finding the correct formula and then plugging in.  This is a big mistake.
Expert problem solvers first go through a process of looking at the physical
situation, making drawings, diagram ... and the last step might be using a
memorized equation.  When problem solving is reduced to equation hunting,
student thinking is moved to the lowest level, and students have no way to
realistically check if the solution is correct.

The Hellers have produced a good method of attacking this problem
http://www.physics.umn.edu/groups/physed/Research/CGPS/CGPSintro.htm .
Unfortunately their material is far too advanced for your classes or typical
HS classes, but their website might be useful for your information.  I would
recommend looking at the "Minds on Physics" series, Leonard et al. for a
good example of expert problem solving aimed at the HS level.  MOP also uses
some very good strategies that challenge students to read word problems
correctly.  Part of the difficulty is that telling students to use formula A
in problem b and c encourages memorization and discourages analysis.  They
will then fail to realize that problems c through h may need the same
formula.

MOP also reverses the typical textbook writing, by deliberately making some
of the language more difficult rather than dumbing it down.  They use
sentences where several nouns are used, and the student has to figure out
which object is the important one.  This is distinctly different from the
typical HS text where the problems have been pared down to skeletal
structures.  Some students just look for the nouns and then hunt for an
equation that has those things.  MOP and the "rich context problems" of the
Hellers force students to hunt for meaning rather than equations.

As far as graphs goes, most of the reformed curricula attack this problem
fairly well.  However I am convinced that students must do some graphing on
paper by hand.  There is a distinct tendency for some students to put the
points at grid intersections and then distort the scale so all graphs come
out as straight lines.  This is probably a failure that has 2 roots,
laziness or hastiness, and a lack of understanding of proportional
reasoning.  In the end lack of proportional reasoning ability places the
student at an extreme disadvantage.

Without proportional reasoning algebra skills alone will not be very
helpful.  Some of the problems with algebra and math reasoning are
highlighted in http://www.mste.uiuc.edu/murphy/Papers/ and
http://ericae.net/edo/ED313192.HTM

John M. Clement
Houston, TX

> As I can see from my mailbox, lots of people have opinions on
> this.  But here is mine anyway.
>
> The biggest problems with my students are
> 1.  They have no idea how to systematically solve a problem.
> Have no idea what the problem says or what to do with it.
>
> 2.  Even when told what equation/formula to use with a problem,
> students don't seem to be able to know what to do with the
> numbers and the variables.
>
> 3.  I have yet to meet a student that can graph data and
> interpret data.  It is not like I have them doing graphs by hand;
> they can use excel.  But they have no idea about the "line of best fit"
>
> 4.  Forget about any kind of graphical interpretation.  Graphs
> mean very little to my students.
>
> 5. Lack of study skills.
>
> If I were to teach a physics class in high school, I would emphasize
> 1.  How to read, interpret and answer word problems.
> 2.  Heck, while I am at it I would make sure they have the basic
> algebra skills to solve said problems.
> 3.  I would work on making graphs of data and being able to
> interpret the data.
> 4.  More on graphs and how to use them.
> 5.  More problem solving skills.
> 6.  How to study physics.
> 7.  Vectors are friends.
>
> I think the amount of material varies.  On one hand, I think
> there should be many topics covered quickly for the exposure but
> on the other hand if you cover a topic, you should cover it well
> and correctly.
>
> I have students come to me and say my high school physics teacher
> did it this way.  Most of the time it is wrong.
>
> I would go towards more hands on activities too because they wont
> see them in college for the most part.
>
> Most of my first year students haven't experienced anything in
> the way of physics so ...
>
> All I know is that I would emphasize graphs and critical thinking
> skills because those are transferable to other fields
>
> Tina and her opinion
>
>
>
> > > What should students have experienced as they enter a first-year college
> physics course?  The question relates to students who plan to study
> engineering or physical science as well as to those who do not.  I also do
> not mean to confine the discussion to a list of "important topics" but
> instead wish to include opinions on skills such as
> problem-solving and data
> analysis.<<
>
>
> Tina Fanetti
> Physics Instructor
> Western Iowa Technical Community College
> 4647 Stone Ave
> Sioux City IA 51102
> 712-274-8733 ext 1429