Yingwen,

I believe you've captured the essence of what I was originally saying ... that humor in the classroom is a tool for controlling the initial introduction of the material to be learned and, thereafter, to more or less guide the general "learning attitude" of the student body.

I loved something else you said, at the outset of your dissertation ... that LIFE, itself, is very serious and that humor plays a large part in it. I dare say, were it not for our innate sense of humor, so many more of us would find ourselves totally incapable of surviving many of life's everyday challenges. Ergo, stiff-necked, ultra-authoritarian approaches to dealing with students--albeit most effective in the military where DISCIPLINE supersedes all other objectives--is surely NOT the answer in the ESL realm. After all, ESL IS a business, while it's more pleasant to see "customers" with smiles on their faces rather than anger or confusion. In the final analysis, the employment of humor and the intensity of one's teaching style are simply matters of common sense.