(I was going to post this earlier, but the gerbils at my ISP seem to be sick…)
There are some very real reasons why teachers are considered less intellectual than, say professors, doctors, or business people.
1.) As was mentioned, it is hard to stay current in your subject as a teacher. After you get certified, you spend a large chunk of your time staying current in your field (teaching). Sadly, this is somewhat counterproductive in that much of the “current” research in education turns out to be bunk.
2.) There are people who tried to become _______, and couldn’t do it. These people take up teaching as a “fall-back career.” (My father, for instance, got his masters before his PhD just so he could teach in case he didn’t do well in his doctoral program.)
3.) Very often, those who go into teaching who are considered more intelligent are pushed up and out. (i.e. into Administration or Teacher Education) Very often, the pay and/or benefits are better than those for a classroom teacher. The economic incentive is to not stay in the classroom.*
4.) There are some teachers who know the system well enough to be in at 7:30 and out by 2:30, with nothing to take home. These folks come from all subjects; most other teachers tend to view this as scamming the system.
5.) It is certainly true that the knowledge set you need to have in your subject does not need to be as large as the set held by people “in the field.” What most people fail to remember is that you must have a complimentary knowledge set in educational methods. As has been noted, there are some professors who are whip-smart, but cannot communicate effectively in a classroom. A good teacher needs to be able to communicate effectively with students of all different learning styles. (Although, you may remember my rant from another thread about the utter uselessness of requiring teachers to be able to do this to the degree that our system does.)
OTOH, the dicotomy of the views many people have about teaching is really funny. I hear “yeah, but you guys get summers off” or “those who can…” fairly often. My response (which is surprisingly effective) is “you know, there is a shortage of teachers. In fact, in math, science, or foreign language, you have a good chance of being hired with no certification. If you like the benefits of being a teacher, why don’t you become one?” It is absolutely amazing how many people immediately back pedal. “I could never teach; I’d kill the little bastards!” (usually said by a parent, btw…) or “No way could I teach 3/4/5 different subjects in one day.” (usually said by those in higher education) or “I could never give 5 presentations in one day.” (usually said by those in business; and I correct them: it’s five presentations every day…)
*Personal anecdote, very similar to what LHoD said:
I get asked “Why are you teaching?” all the time, for all different reasons. By everyone. Not just by “regular people,” but by my colleagues and bosses, as well. There is a very common sentiment that teachers who are “more academically inclined” do not stay teaching.