ANGELS ON A PIN

This delightful vignette is excerpted from Dr. Alexander Calandra's recently
published book, The Teaching of Elementary Science and Mathematics,

 

Some time ago I received a call from a colleague who asked if I would be
the referee on the grading of an examination question. He was about to give a
student a zero for his answer to a physics question, while the student claimed
he should receive a perfect score and would if the system were not set up
against the student. The instructor and the student agreed to,an impartial

arbiter, and I was selected.

I went to my colleague's office and read the examination question: "Show
how it is possible to determine the height of a tall building with the aid of
a barometer."

The student had answered: "Take the barometer to the top of the building
attach a long rope to it, lower the barometer to the street and then bring it
up measuring the length of rope. The length of the rope is the height of the
building."

I pointed out that the student really had a strong case for full credit
since he had really answered the question completely and correctly, On the
other hand, if full credit were given, it could well contribute to a high
grade for the student in his physics course. A high grade is supposed to
certify competence in physics, but the answer did not confirm this, I suggested
that the student have another try at answering the question. I was not surprised

that my colleague agreed, but I was surprised that the student did.

I gave the student six minutes to answer the question with the warning
that his answer should show some knowledge of physics. At the end of five
minutes, he had not written anything. I asked if he wished to give up, but he
said no. He had many answers to this problem; he was just thinking of the
best one. I excused myself for interrupting him and asked him to please go

on. In the next minute he dashed off his answer which read:
"Take the barometer to the top of the building and lean over the edge of

the roof. Drop the barometer, timing its fall with a stopwatch. Then using the
formula S = 4 at’, calculate the height of the building."

At this point, I asked my colleague if he would give up. He conceded, and
gave the student almost full credit.

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