That's fucking stupid. I hate racism, and I don't think that teacher was out of line or anything. There were no ill intentions, and anyone who takes it the wrong way should get the fuck over it.

I should also mention, I've gone to school in the Georgia public school system, and a lot of those teachers are blatantly fucking racist. Regardless, this was a history teacher and the students were learning about that era in time. It isn't as if the teacher allowed the students to wear the robes in class as a joke or something. This is definitely an example of "zero tolerance" at it's finest. Fucking bullshit, IMO.