Re: Arbitrary Grades?????

[flemmerhirt@mail.wcc.cc.il.us (Fred Lemmerhirt)]

For some years now I have been using a lab exam to determine lab grades,
as described by Steven Ratliff.  I ask students to maintain a lab
notebook in which they are to record all data, do all calculations and
graphs, and express all conclusions and comparisons, knowing that they
will later use the notebook during a lab exam at the end of the
semester.  Some exam items are rather trivial  (What was the ID number
of the ammeter you used in the e/m lab? . . . What is the "book value"
of the resistivity of copper.), just to see if routinely required things
have been recorded.  Others are a little more substantial (Sketch the
graph of resistance vs temperature that you plotted for the thermistor.
.. . From the graph shown here, determine the temperature coeffecient of
resistance.).  Some are problems in which a result is to be calculated
from some sample data, following a procedure that was used in one of the
labs.

Ideally, students who do the labs most thoroughly and thoughtfully and
maintain their notebooks most carefully and completely will do best on
the lab exam.  Actually this does seem to be the case, in the sense that
the students I observe doing the most careful work are the same ones who
do score best on the exam.

In the end, the exam determines about half the lab grade, with the other
half being earned by just having done the labs.  (At the end of the lab
exam, I collect the lab notebooks and check them for evidence of "gross
negligence", such as omitting a graph entirely, and deduct points
accordingly from this latter half of the lab grade.)

While this is certainly not a perfect system, I've been more satisfied
with it than with anything I had tried previously.

Fred Lemmerhirt
Waubonsee Community College
Sugar Grove, Illinois



Steven T. Ratliff wrote:

> To:  Phys-l
>
> Regarding:  Grading Lab Reports
>
> 1.  I try to assign some questions with the lab experiment.  These
> can then be graded and help to determine the overall grade.
>
> 2.  One interesting idea that I have not tried yet (but might in the
> future) is to give a lab final exam.  In this system, the lab grade
> comes from (1) completion of the experiments, and (2) the lab
> final.  The individual experiments are graded perhaps only on
> completeness, thus avoiding the problem of how to grade the
> individual reports.
>
> Does anyone else have any comments on lab finals?
>
> Regards,
> Steven Ratliff
>
> Steven T. Ratliff
> Associate Professor of Physics
> Northwestern College
> 3003 Snelling Av. N.
> Saint Paul, MN  55113-1598
>
> Internet:  stratliff@nwc.edu (or str@nwc.edu)