I have just seen this post on Inside Higher Ed website, so I thought it will be a nice note to end the semester with a smile. Or at least a reflection upon it, and a smile already ready for the start of the next semester.
I personally cannot imagine lecturing without an occasional humorous comment. We all deal with frequently difficult and serious academic topics. But I don’t see the reason why we shouldn’t smile from to time while discussing them. And after all, the psychological benefits of smiling are probably far greater than any potential undermining of the learning topic. Of course, there are always exceptions and situations when teacher needs to be firm and reserved, but in general, I would always recommend smiling over all the other facial expressions.