In my high school classes I use a "flub stub" technique. I start it the first
day. If a student finds, during the lecture, that I have made a mathematical,
symbological, or conceptual error (mispellings, misspronounciations, etc don't
count.) and can state what it should be then they get a printed certificate
worth 2 pts on homework or lab assignments.
This, which is not original with me, technique accomplishes three things. It
lets the students know, on the first day, that I, like themselves, make
mistakes. It forces me to be much more careful and not get away with
generalities or handwaving. And best of all, they pay attention!! I'd like to
think they pay attention because of my brilliant lectures but I'll settle for
them paying attention to get 2 pts.
Is it bribery? yes. Am I putting myself in a bad position by admitting I make
mistakes. No. I'm just being truthful. I've never had a complaint yet except
when I overrule them because I was right or they were wrong.