According the news story on TV here in Dallas, the complaining students & parents were black. http://video.nbc5i.com/player/?id=176316
I personally have an issue with blacks being able to call each other the "N" word and having it be acceptable. I was very pleased when some of the local Black leaders took a stand against Black youth using the word to refer to each other. IMO, it's all about respecting each other. And I could go on and on about my feelings on that.
"History is bound to repeat itself" is an old quote referring to the fact that we fail to learn from mistakes of the past. It is hard for me to imagine a time when people were considered property. Separating family members, physical and emotional abuse, lack of opportunity for a better future, all of this is important for us to understand how and why it happened. If we don't help people to understand why it occurred and why it was wrong, it will happen again to another group of people. And again.
I am not defending the teacher as I wasn't there and I don't know what was said or how. I am probably too chicken to teach the subject to a group of students, though I have discussed it with my children.
If it makes any difference, I am part Cherokee, female and older.