My guess is that you've never been in the situation to do this. Coming up with good problems, unambiguously stated, that address the points you wish to address and not the ones you wish to skip, is very difficult. Especially at the undergrad level, where you have to be careful because the base of knowledge is so small (or, at least you have to assume it is).
If the professor has to constantly come up with brand new problems, the students are forever seeing rough drafts of unvetted exams.
Here's a very simple example of a failure I had that illustrates the kinds of things that can unexpectedly go wrong: "what is the angular speed of the second hand of a clock?"
After struggling for a long while with this question, a very bright Asian student finally asked, me: "I see three hands on the clock: obviously they are the first hand, the second hand, and the third hand. Can you please tell me which one you are calling the second hand?"
At the graduate level it may be easier (I've never written a graduate exam) because, fuck 'em, they're grad students, let them deal with it.
You make a good point. I wish all exams/quizzes were composed of carefully thought out questions.
In my experience most such questions are simply intended to verify a cursory familiarity with the subject -- or to be easily graded. Easy grading is another aspect of laziness that ought to be done away with.
Why must an exam be multiple choice rather than essay answers? Only so it can be chugged through a machine so nobody has to think while grading it.
I agree, but it is much harder to make up a thoughtful mc exam. I have done it when I was trying to prepare students for a standardized exam (MCAT) and it was a real bear. I'm not sure it was the right thing to do (I no longer do it), but that was my intent.
If the professor has to constantly come up with brand new problems, the students are forever seeing rough drafts of unvetted exams.
Here's a very simple example of a failure I had that illustrates the kinds of things that can unexpectedly go wrong: "what is the angular speed of the second hand of a clock?"
After struggling for a long while with this question, a very bright Asian student finally asked, me: "I see three hands on the clock: obviously they are the first hand, the second hand, and the third hand. Can you please tell me which one you are calling the second hand?"
At the graduate level it may be easier (I've never written a graduate exam) because, fuck 'em, they're grad students, let them deal with it.