The discussion about partial credit grading has brought the hypothetical
engineer into the discussion. I am a real engineer, I have taught
mathematics in community college, and I give partial credit. First, let's
look at the nature of engineering:
If you are a certified professional engineer designing a safety-related
structure, someone will check your calculations or they will be done with a
computer-aided calculation package. The calculations will be right.
What matters in a case like this is whether the engineer has seen all the
possibilities and done all the relevant calculations, not whether he has
gotten a particular calculation right. The classic bridge example is the
Tacoma Narrows Suspension Bridge, which failed due to an unexpected resonance.
By the way, the engineer who designed the bridge did recognize what the
problem was shortly after the resonance began in a light but steady wind,
and formulated a solution that would have saved the bridge. The authorities
prevented him from implementing his simple solution because they would not
allow him (or any one else) out on the bridge because it was too dangerous -
as if the bridge's designer didn't know exactly how dangerous it was.
Shortly after the bridge's collapse, he committed suicide.
My engineering career was somewhat different. I designed electronic
instruments (or parts of them) for Hewlett-Packard. If I did a calculation
wrong, the circuit didn't work - and I did build every circuit I designed.
What mattered in my case was whether I had taken all the possible component,
temperature, and usage variations into account so that with normal
manufacturing tolerances the product could be manufactured to specs and
operate dependably no matter how the customer used it.
Though my product was very different from a bridge, the focus was the same.
The bridge designer must produce a single, untestable design that must work.
My work involved a somewhat testable design that nevertheless could not be
completely tested because it involved knowing (or imagining) all possible
tolerances and ways of use.
So, if an engineer doesn't get the answer right the first time he does a
calculation, it really doesn't matter (usually). Someone will check it or
he'll find out that it doesn't work. He (or she) will eventually get a
correct answer, it just might not be a complete answer. The good engineer
doesn't just do one calculation right, he must understand the problem and
know what questions to ask.
OK, so I'm now semi-retired, and I taught "intermediate" algebra at the
local community comunity college (AIMS) for a year or so. I gave partial
credit because I thought I was supposed to teach algebra, and some of the
students couldn't do arithmetic. They seemed to understand the concepts of
algebra, but they couldn't factor a polynomial because they could not do
simple arithmetic (2*3=5). I could give partial credit, or I could teach
arithmetic. I also took off credit for the right answer with no support.
In every class there was at least one student who seemed to know what he was
doing, but could never learn to show his work. That is, this kind of student
could not write down a coherent explanation of how he solved a problem.
That student would have made a lousy engineer.
Yours truly,
Randy Hudson
P.S. Bicyclists check out my Web Page at http://www.verinet.com/~pedal
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