What should be done about a professor who treats foreign students worse than domestic students? My school and my department has a lot of undergraduate students from China. When I took this instructor's class, he routinely


pressured the foreign students to answer questions about their home country that they weren't comfortable answering. (This is a math department; his questions weren't relevant to the course.)
pressured the foreign students to quickly answer when they struggled to either understand him or respond in English. 
sneered when they answered one his questions wrong, no matter how strange the question was. 
didn't accept "I don't know" from Chinese students.


He never did this to any of the domestic students. This was a topic of discussion among the American students before his class—we all noticed it. Several Chinese students dropped his class because of the way he treated them, but they didn't complain because that isn't considered kosher in China. (He actually said, "I don't understand why 'A' students are dropping," after a very talented Chinese student withdrew from this class.)

I can't point to any one thing he said or did that clearly crosses the line—I would have reported him to the dean's office and the department chair if he had—but he came up to it too many times for me to be comfortable with his behavior. I liked the guy in the beginning of the course, but I was sick of the way he treated my Chinese friends by the end.  

To summarize: I feel this adjunct's behavior towards Chinese students borders on harassment, but isn't obviously harassment. Should I do anything? What?

To clarify—this class already ended, but I'm told he still keeps up this crappy behavior. And the Chinese students actually come from mainland China.
Your university almost certainly has an office devoted to considering situations of racial harassment and discrimination. If the behavior is in general towards international students rather than just Chinese ones, this is usually also explicitly prohibited as "national origin" rather than race. You should Google your university name along with the phrases "civil rights office" or "discrimination." Usually you can make a report to them, often anonymously, and in theory you ought to be protected from retaliation.

Note that from what you've said here, I would be surprised if serious action was taken against the professor -- his actions were bad but no single action crosses the line, you say, and behavior like this is sadly common. However, it may result in a reprimand (which can, after all, change behavior if he feels pressured). In addition, I would encourage you to make this report so that, if his behavior ever escalates, there will be a case history. So often I read stories about harassment cases in academia where the defense is something like "well this was just one offense" and it seems it almost never is in reality; just the first one reported. If you say something, then the next person who says something (and may have a more serious complaint) is more likely to be believed.