That's how I "break the ice" with any black person I meet. I always start off with the knee-slapper, "What about the KKK, what the sheet was that all about?"
Or when I meet a Jew for the first time, I always ham it up with, "Hey, wasn't Hitler a funny guy? He could just kill you!"
This teacher should be fired on the spot, but she won't be. She's female, she's black, and she's union. So, she's untouchable.