By Daniel T. Parker, Korea
Knowing or not knowing all the technical mumbo jumbo doesn't necessarily mean that one will or won't teach well.
Teaching requires several elements, one of which is a necessary amount of knowledge about the subject taught. How much is necessary depends largely upon the level of the learner. I teach university students in South Korea, and most of my students are in the English Language and Literature Department, and many of them take TESOL courses. One of my colleagues is an enthusiastic teacher and very personable, but can't explain grammar to writing students and can't tell the difference between voiced and unvoiced consonants to conversation students. I'm not saying she can't teach! But it does frustrate some of her students; I know this because they come to me.
Earlier this week I had a student ask me a question about "approximants." I didn't remember the term, looked in my old linguistic textbook and couldn't find the term, then looked in her new textbook and found the information; bingo, I was able to craft a satisfactory explanation and offer extra examples.
On the completely other end of the coin, I have taught special courses to people who teach elementary English here in Taegu. Some of them are very good in English, some are fair, some of them can't carry on a simple conversation about time, clothing, weather, etc. Does this mean they are bad teachers? No, it's insufficient data to answer the question.
But many of them were fascinated when I started explaining where and how different sounds are made. With all of their conversation classes in college, no one had ever taught them that. It didn't mean they were able to immediately correct their own pronunciation.... but, one of my students took the time to write me a short note basically saying this: "Before, I could only tell if my student was or wasn't making the correct sound; now, I can tell them how to make it correctly."
But remember: if I go into their 1st, 2nd, 3rd or 4th grade classrooms and start talking about glottal stops, affricates, transitive verbs or passive voice, I won't have taught their students a darned thing by the time I'm kicked out.
So here's my ultimate point: being a good teacher requires more, much more, than knowledge of the subject one teaches. However, a good teacher can and will become a better teacher by learning as much as he or she can about the subject.