Right after I submitted my last post, this showed up in my email:

It might not be entirely accurate or perhaps just a legend, but it's a

great story about learning how to think differently.

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Some time ago I received a

call from a colleague. He was about to give

a student a zero for his answer to a physics question, while the

student claimed a perfect score. The instructor and the student agreed

to an impartial arbiter, and I was selected.I 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 it to the street, and then bring it up, measuring the length

of the rope. The length of the rope is the height of the building."

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 in his physics course and to certify competence in physics, but

the answer did not confirm this. I suggested that the student have

another try. I gave the student six minutes to answer the question

with the warning that the 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 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 x=0.5*a*t^^2,

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. While leaving my colleague's office, I recalled that the

student had said that he had other answers to the problem,so I asked

him what they were. "Well," said the student, "there are many ways of

getting the height of a tall building with the aid of a barometer. For

example, you could take the barometer out on a sunny day and measure

the height of the barometer, the length of its shadow, and the length

of the shadow of the building,and by the use of simple proportion,

determine the height of the building." "Fine," I said, "and others?"

"Yes," said the student, "there is a very basic measurement method you

will like. In this method, you take the barometer and begin to

walk up
the stairs. As you climb the stairs, you

mark off the length of the

barometer along the wall. You then count the number of marks, and this

will give you the height of the building in barometer units." "A very

direct method." "Of course. If you want a more sophisticated method,

you can tie the barometer to the end of a string,

swing it as a

pendulum, and determine the value of g at the street

level and at the

top of the building. From the difference between the two values of g,

the height of the building,in principle, can be calculated." "On this

same tact, you could take the barometer to the top of the

building,attach a long rope to it, lower it to just above the street,

and then

swing it as a pendulum. You could then calculate the height

of the building by the period of the precession". "Finally," he

concluded, "there are many other ways of solving the problem.Probably

the best," he said, "is to take the barometer to the basement and

knock on the superintendent's door. When the superintendent answers,

you speak to him as follows: 'Mr. Superintendent, here is a fine

barometer. If you will tell me the height of the building, I will give

you this barometer." At this

point, I asked the student if he really

did not know the

conventional answer to this question. He admitted

that he did, but said that he was

fed up with high school and college

instructors trying to teach him how to think. The student was Nobel

prize winning physicists Neils Bohr.