We've had some lengthy debate about this during coffee breaks. The Division of Natural and Applied Sciences at Bluffton University includes physics, chemistry, biology, mathematics, dietetics, and pre-medicine, so our coffee breaks include a wide range of professors.
We have proponents ranging from no points off to all points off. You might find it reassuring that the dietetics profs tend to be sticklers for getting it right because their computational errors could affect someone's health. On the other hand, the biology profs tend not to take off any points for wrong arithmetic and decimal errors, and that's somewhat unnerving because most pre-meds are biology majors.
My philosophy is that you need to take off some points because not doing so seems to imply it is not necessary to be careful, and/or it is not necessary to get it right the first time. We seem to be a society in which "do-overs" are a way of life... except, of course, when the error ended someone's life or perhaps bankrupted them. Do-overs are pretty difficult in those cases.
When a student makes a math error in what otherwise is correct physics, I lower the grade on that problem sufficiently that the score on that problem is a B rather than an A. Some students think that is harsh, but I want the penalty to be stiff enough that they are forced to be more careful in the future.
What I don't do is keep taking off points if that error propagates. If they use the wrong number in a later portion of the test and therefore get a second wrong answer, I mark it "wrong but consistent" and I don't take off points. Unless... unless the later answer obtained with the wrong starting value is absurdly wrong and anyone who knows what they are doing should have recognized that the answer couldn't possibly be right. In that case I don't take off points for the wrong answer; rather, I take off points for not recognizing that the answer is absurd.
Michael D. Edmiston, PhD.
Professor of Chemistry and Physics
Chair, Division of Natural and Applied Sciences
Bluffton University
Bluffton, OH 45817
Office 419-358-3270
Cell 419-230-9657
-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Aburr@aol.com
Sent: Tuesday, March 22, 2011 1:22 PM
To: phys-l@carnot.physics.buffalo.edu
Subject: Re: [Phys-l] docking for correct thinking
true
yet there is the infamous NASA experiment which had all correct reasoning but used the wrong units at the start. Cost Millions.
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since this is a learning experience, I would probably give points for the correct reasoning.
Alex. F. Burr
In a message dated 3/22/2011 11:07:58 A.M. Mountain Daylight Time, bernardcleyet@redshift.com writes:
You've docked them for "correct" thinking, not a good message