Lightbrite, silence sometimes means that the comment does not deserve an answer. If the teacher expected a laugh and was met by stone faces it was probably the greatest punishment she could have received. In an case, teachers can also be recorded and the comments uploaded to YouTube. Evens if teachers have tenure their classes can be boycotted.
As for retribution for opposing the teacher’s beliefs, I got in trouble with my 11th grade English teacher for writing an essay about why we should not have to study literature. I would imagine that one would get in trouble with a frum teacher for opposing his particular hashkafa. Of course, in the hard sciences this is not an issue. In any case, in college there are generally lists of teachers of the various courses and there are ratings available on the Internet.