Frankly, I don't buy the professor's explanation that she wore blackface to a Halloween party to teach about Damon Tweedy. Isn't the classroom the most appropriate venue for teaching something that significant, and doing it without blackface, especially if you are white? Halloween parties are ostensibly frivolous fun events, not a place for teaching anything like what she claims, therefore, I think she came up with this excuse ex post facto. 

But the most important question I would have for the professor, is why? Why did you not know that wearing blackface, even at a private party, was at the very least in poor taste and bad judgment, knowing the history of blackface in American history and culture? Why, especially as an educated white person in the U.S., did you not know that it is considered racist? If an African American person wore a doctor's coat with a name tag that said "Dr. Tweedy", that would make sense. But a middle-age white woman wearing blackface in the year 2016?