Sociolinguistics and Teacher Self Awareness

I was in a colleague's classroom when I witnessed something that absolutely is a perfect example of the lack of cultural awareness/sensitivity on the part of many teachers working with diverse populations. An African American student said to his white, middle class teacher "Is we going to lunch?" The teacher made this huge deal, calling out the child and embarrassing him in front of the class. She informed him that that was not the correct way to speak. Then she said "We're fixing to go to lunch as soon as you get where you're supposed to be at!"