Recently there have been a number of posts about the strategies which
students employ to solve assigned back of the chapter type problems. In
addition there have been posts about whether we should demand a
particular set of rules to assist students in structuring their problem
solving approach or allow the student to "discover" a methodology which
works for them. I have been cogitating on these issues over the last
couple of weeks and since i have no other physics teacher around here to
talk to about these issues i am going to dump my confusion on you.
Many of us believe that one of the most important skills we can teach is
the ability to reason through a problem, to develop problem solving
skills. This involves, critical reading, an ensemble of approaches to
assist with working through the issues surrounding the problem, the
ability to know when to give up a particular approach etc etc. This is a
most difficult thing to teach and an even more difficult thing to assess.
If left to their own devices many students will develop problem solving
strategies which are both ineffectual and contradictory to our goals of
teaching critical reasoning skills. They will do anything to arrange the
variables to get the back of the book answer, they will ignore any
quantity which is one, they will skim the book for pattern matching
examples etc etc. These are not the problem solving skills/strategies
which we want to develop.
As part of my responsibilities in developing systems for a large business
i required all of my technical employees to attend training in ways to
solve problems. Although the strategies which they learned were not
applicable in every situation it provided a framework from which they
could at least begin to explore their options. Over the last couple of
years i have come to the conclusion that we need to teach these
strategies (or rules as some have said). For the marginal student it
will provide them with at least one problem solving strategy... better
than the above litany of common student methods.
With this in mind i am starting to use the "clean sheet" method: these
include...
1. Start each problem on a clean sheet. (We all know of many cases
where a student (or ourselves) tries to cram a problem in a small space
causing errors in calculations or dropping an exponent etc) Yes they will
moan and cry over this one.
2. What is known.... What is known and necessary, what is known and
possibly valuable, what is known and probably not necessary.
3. What is it that you are trying to find.
4. A sketch of the situation with all knowns and unknowns identified in
the sketch....
5. A quick estimate of what you are trying to find..... (this is very hard
for them)
5. principle/laws involved in the solution
6. solution, approach, equations, graphs etc.....
7. Is this answer reasonable.....
I wont bore you with the complete set of rules, they are fairly obvious
to us. The better students will use this approach when necessary and
will learn to modify it when it does not work. The other students will
at least have one "tool" in their tool kit to work with.
I also require students to always have graph paper in their kit, i
encourage them to spread out when doing problems.... (not on the bus on
the way home (they can do their social studies homework there)). I
encourage the use of study groups, and we discuss how study groups should
work.
Every quarter they are also given some (one or two) open ended types of
questions which require them to use these skills in a less structured
environment. (i.e. how much electrical power is created by the Glen Canyon
Dam and how does that relate to the height of the dam and the amount of
flow in the river)
Bruce Esser
Physics Teacher Something witty
Marian High School Should go here
Omaha NE http://marian.creighton.edu