That's a weird story. That teacher's behavior seems... well, either he/she is mentally ill, or needs to be fired, but either way, needs to be pulled from the classroom, if that's accurate.
I'm not sure what the class is, but it's pretty common now for undergraduate institutions, particularly liberal arts programs, to have "race and ethnicity" requirements. Basically it typically involves taking a course that explores an academic topic from the non-dominant perspective. Like in psychology, courses that explicitly deal with doing therapy with people who come from outside the dominant culture, or psychological research of race and ethnicity. In literature it might be a class that looks at major contributions from non-Caucasian American writers (like Morrison and Hurston and others) who are very important in the American canon, but are often not included in traditional literature reviews. And so on.
In my experience, it's usually been something that can be incorporated in a way that enhances the curriculum. When I was an undergrad at Michigan, the liberal arts college (LSA) had such a requirement, but the engineering college did not. I still ended up taking a course that would have met the requirement as part of my humanities electives. Now, I think I'm on the hook for meeting this sort of requirement for the American Psychological Association, in pursuit of licensure in the future. But I may have already met it with an African American Psychology class, which was actually really valuable in any event.
I'd guess that at the high school, it's just a class that rounds out history and/or sociology by talking about the parts of our culture that don't get enough play in history books that concentrate on the links between the wars and the presidents and Europe and the Americas, and so on.
