One of the few consolations of exam marking is the innocent fun we get from things our students write under the stress of exam conditions.
I think the students are getting better, since such moments seem to be rarer. Here are a few gleaned from the last couple of years’ Number Theory scripts.
- The value of this infinite continued fraction is infinite and gets successively smaller. [Come again?]
- x^{2}+y^{2} = p, where p is prime, if and only if the squarefree part of p is a quadratic irrational. [This is someone trying to touch every base in the course, I think.]
- √2 is an infinite number. [Eat your heart out Cantor, Pythagoras beat you by two millennia!]
- Primitive root means we have to find the power. [I feel a superhero adventure coming on…]
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My favourite exam story (I only use multiple choice now, so all such stories are old ones) is a class of about 200 who together wrote 59 different wrong spellings of Dijkstra. My favourite was “digestra”, which sounds like some kind of fat substitute.
From Linear Algebra III a couple of years ago:
Q. State what it means for a matrix to be Hermitian.
A. It lives by itself under a bridge.
From Linear Algebra I, slightly more recently:
Q. State what it means for \lambda to be an eigenvalue of a matrix A.
A. It is the key to the matrix’s inner soul.
(The latter is of course quite a profound statement, in its own way, but it wasn’t quite the answer I was looking for…..)
I probably told this story already, I can’t remember.
The first course I ever taught was differential equations at the University of Michigan. I had to make up a quiz, and was one point short. So I asked, “Do you know Abel’s identity?” The idea was that anyone who said “Yes” got the point, and anyone who said “No” got a point for honesty.
Two students said, “Son of Adam and Eve”, I gave them two points.