Well, Mo’ Joe:
Sweetie, having never met me, you don’t know how I would speak in a given situation. Also, you assume that I teach kids, which I don’t currently. But that aside, I could counter by saying that usually grammar and formal speech are not what many schools have difficulty teaching. Presumably a school would hire me because I have the knowledge their non-native English speaking teachers don’t; that is, the living, breathing language of the day. Non-native speakers want to hang around me because I can teach them how to understand the things they thought they learned but don’t understand because it doesn’t follow the “rules.” Every single non-native speaker I’ve communicated with here in my lovely hometown and abroad complains that they are full of book knowlege but the real language they run into every day makes their heads spin.
You could be right about going for a job interview; however, my 24 year old niece’s boyfriend had an interview a while back with a small computer firm and he was laughing because one guy referred to him as “Dude”! By the way, he got the job and his official title now is “Dumb-ass Three”.
So my dear, I beg to differ with you. It all depends on the teaching assignment. If I teach business English, I’m gonna research the common language of that environment and incorporate whatever variations I find. If I’m the sole provider of instruction to little kids, of course they need the basics, but that won’t preclude me from introducing some slang phrases for our enjoyment (well mostly mine, there’s nothing cuter than a 6 year old greeting me with “WAAASUP”?!)