lab grades

Bob Vickery vickery at JOLT.MPX.COM.AU
Mon Oct 27 07:11:15 EST 1997

mclaugh at <Esther G. McLaughlin> wrote in reply to the original
poster whose name I seem to have lost:

>>Most classes that I teach have laboratory components.  In general, students
>>spend approximately equal amounts of clock time per week in both (i.e. 3
>>hrs classroom + 3 hrs laboratory).  In my general biochemistry class,
>>approximately 70% of "total points earned" are from lecture quizzes and
>>examinations, while the remaining 30% are based on lab quizzes and reports.
>>Although I feel strongly that the laboratories are a very important
>>component of the course, it seems to me that my grading policies don't
>>reflect that commitment; I sometimes suspect that as a consequence of this
>>grading bias students may view labs as being of secondary importance.
>This has bothered me for years:  biology is not an abstract subject; real
>experiences (of many kinds) should be the center of any bio course -- but
>this is easy to say. Some institutions have found that eliminating labs
>saves lots of money. Many of us think this is either immoral or
>pedagogically nuts (or both). I have tried to weight labs to be worth about
>as much as the "lecture" portion of my courses, although often it's more
>like 40:60 rather than 50:50. I did give the lab greater value than the
>lecture in a plant pysiology course once. I had a positive reaction from
>one student (on the anonymous course evaluation), who was impressed that a
>bio course finally paid sufficient attention in grading to the part the
>students spent the most time & effort on. We shouldn't expect students to
>value lab work if we don't give it much value when we grade.
>Esther McLaughlin

Practical exams that include section cutting, drawing, identification of
unknowns, and so on, are much more discriminatory than theory exams using
essays and multiple choice.  That is, the deviation of marks between the
best and worst in the class is much greater.  The outcome is that the
practical marks  have a disproportionate influence on ranking within the
class and the award of distinctions and credits.


Bob Vickery
bob at
vickery at

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