1) i'd say racist is as racist does. i think it takes more than one snotty comment to make someone a racist. it may have been an insensitive remark, however. to be racially insensitive, i think it would need to be determined that you only correct minority kids.
when i was in school there were teachers who wanted to be cool. teachers who enticed you with their love of learning and sharing. teachers who made snotty comments instead encouraging ones. people are different. it was the end of the day and it is not something you do all the time, so i say no biggie (not that "biggie" is a word, mind you). i do think teleharmonium's line - in this class we say "ask" - is a better choice cause it doesn't put the kid down and it establishes that you are speaking about your classroom and not some larger authoritative structure. i support staying specific.
2) i do think teachers should make kids aware of the different choices one makes based on things like language use or clothing. those choices will affect how one is perceived when job hunting (and, of course, different dress and language will be appropriate for different job interviews). i like, maki, what you said about the three different uses of language.
3) when it comes to language, i am a descriptivist. a living language is always changing. "proper" language has changed plenty over the years. how would one draw a line to say where we make the cut between archaic and proper and modern, inappropriate slang?
i support knowing what is generally expected in different settings so one can make the best choices depending on that person's specific goals in that situation.
however, i think language has probly some of the most arbitrary rules. this is why i like the descriptivist/prescriptivist debate. why is "ax" wrong? why does it sound uneducated or, dare i say, low class? the purpose of language is to communicate ideas effectively (not efficiently). "ax" does communicate the intended meaning, "ask," but it also communicates something about the speaker as well (as does all speech). i think that "ax" is preferable in some situations and bad form in others. in my opinion, this means that there is a larger societal issue at play here. BUT, i don't think it is maki's issue to conquer in his classroom.
and now, just cause, i will point out some arbitrary rules:
This is how we are taught to talk in school.
strunk and white would want you to say "speak in school" not "talk in school." why? heck if i know, but you're the english honors teacher (just saying...).
The answer you're left with trying to explain to a kid, is that there's this right way of speaking, which is determined by a small hierarchy of mostly white elitists in institutions that many people have scorn for.
...institutions for which many people have scorn.
why is it wrong to end a sentence with a preposition? i don't know, but i suspect.... THERE IS NONE! would you blow a job interview if you filled out an app and improperly ended a sentence with a preposition? or answered a question verbally as such? i don't know, but i suspect that the job interviewer wouldn't even notice.
for all the talk about proper language use, i think there are many rules that no one is following anymore....