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Re: 'plug & chug' problems



At 8:25 -0500 7/25/02, Rick Tarara wrote:

6) A great place to move toward true real-world problem solving is the lab,
especially for classes of higher math abilities. For example, I use our
Pasco Ballistic Launchers (mounted on special bases) in an exercise where I
have the students write an equation for the range of the launchers--in terms
of the spring constant. Since the projectile is launched from a height
above the floor but strikes the floor, the kinematics part of the equation
is somewhat complex. Students must devise an experiment to measure the
spring constants--they end up with vertical shots and energy considerations.
When they get it all combined, they put their equations into a spreadsheet,
develop theoretical range curves (function of angle at a fixed spring
compression, function of spring compression at a fixed angle) and then fire
the launchers to get data to compare to their theory.

In other words, moving away from cook-book experiments to more open
investigations and asking for analyses that include developing equations
from the collected data, can provide really useful problem solving
activities. Of course these can't come 'out of the blue'. You need to know
that student can handle simple systems and simple problems before you hit
them with something like the above.

I agree, but even here there are problems with the concept. When
thinking about these ideas, it is easy to forget that the students
have four, five, or even six other courses that are all clamoring for
their time, so "project"-type labs are often difficult to work,
especially if the lab period is just the class period or only
slightly longer, as our are--just 90 minutes, and the same labs are
often used for several classes, so leaving equipment set up is often
not practical. This idea works best when students are already
familiar with lab techniques and are committed to the idea of
learning in the lab. And the class has to have a dedicated lab area
where equipment can remain set up for a week or more, and be
accessible to the students at odd times. A small class also helps. At
the US PHysics Team training camps, the students are given only the
sketchiest lab instructions, and 4 hours to turn out a finished lab
product and complete lab report. They mostly do quite well at it, but
they are also among the best HS physics students in the country. I'm
not sure that students whose mission in the lab is to get the data
and get out as quickly as possible would do very well in this
environment. It takes careful nurturing to turn these students into
ones that will treat the lab seriously, especially when they may also
be taking a chem or biology class in which the labs are still of the
"cookbook" variety.

The trouble with short lab periods is that the students don't have
time to make any mistakes and figure out what went wrong for
themselves. We can't just say, OK, stick around and work on it until
you get it, when they may have another class right after this one.
And they are also getting projects in English and Social Studies, and
perhaps Biology, and many students will also have jobs, some even
necessary for their survival. We are lucky--we are able to forbid
students from taking jobs, or having cars on campus, so we have
eliminated at least some of the distractions that make project labs
difficult, and still we face serious logistic difficulties with
having them.

Hugh
--

Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

(919) 467-7610

Let's face it. People use a Mac because they want to, Windows because they
have to..
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