Pedagogy

I maintain, and will maintain until the day I retire if not longer, that an experience like the following is good for students.

A mathematics instructor, carrying out a lengthy computation on the board, makes a small error, which propagates through the calculation to produce an obviously incorrect result.

He (I use that pronoun for good and sufficient reason) points out and explains the incorrectness to the students. He then gazes at the board for a minute or two, muttering and rubbing his chin, until finally he cries "AHA! IDIOT! IDIOT!" After briefly pummeling himself about the head, he points out the step at which things went awry, and corrects the computation.

I have more than one reason for believing this to be a good experience.

Twice in one lecture, however, may be deemed a bit excessive, even if the instructor is rather less demonstrative the second time.

Everybody's A Critic

I have always thought that my Marvin the Martian impression was a fairly good one.

Murphy seems to disagree.

Chaining

"If you believe in X, do Y. If you do not believe in X, don't do Y."

With all due respect: I do not do chain letters, and I do not do chain posts. You are not entitled to make any assumptions about me on the basis of my failure - my refusal - to do Y.

This is not an expression of anger, or of resentment. I just Don't Do That.