I'm pretty much with you on this.  I think the teacher was intending to have people circle into a discussion where they could see that the word has moved and morphed a little over time, and it has different degrees of insult and power depending on who uses it.  And those are good things to understand and maybe even worthwhile things to ponder while being educated.

But putting the word right up there on the screen, next to a picture of Tupac would seem so utterly probable to be interpreted badly.  What could she have been thinking? 

And surely this is incendiary-enough a topic such that it would have been better to discuss in committee with the other English teachers and perhaps with the Black principal.  That would seem to be common sense.