sentence structure?

[Kabluee]

I have a few educated friends that speak very poor english and it annoys me. I can speak and write it well but it has been years since I had literal knowledge of sentence structure. What rule is being broken by the following sentence?

"Where are you at?"

I know that it is supposed to be:

"Where are you?"

and I have corrected both my friends and their children often enough that I would like to know what rule is being broken?

[mykwyner]

The word at is a preposition, and as such should always introduce a prepositional phrase. Are you at home?

That being said, I want you to know that every English speaker breaks this rule in speech and in writing to one extent or another. They may not break this rule in a manner as egregious as the example you cited, but they break it nonetheless.

There is an old joke in American English where a poor kid gets to go to an exclusive university. On his first day he asks one of the upperclassmen, "Excuse me, can you tell me where the library is at?" To which the snobbish upperclassman replies, "This is Harvard (or the name of any prestige university) and at Harvard we don't end our sentences with prepositions." The new student replied "Oh, I'm sorry. Can you tell me where the library is at a**hole?"

By the way, you have friends who speak poor English not that speak poor english.

[Kabluee]

a lesson learned...lol, as you stated we all make mistakes, that particular one is the one that annoys me the most. Thank you for your reply, I did think that it was a preposition and I will remember the anecdote, to put it mildly, it is not my place to correct them. Sometimes you just need to hear it (or see it in black and white) to see the lesson.

[mykwyner]

Thank you for accepting my light-hearted criticism in the spirit it was offered. I'll be glad to chat with you again at any time.
Mike