Copyrights can be renewed.
And teachers can get fined for breaking copyrights if they don't have permission to make those copies. Does not have to be for resale.
Many academic institutions actually buy permission to make copies (such as universities to put together excerpt/article packets for classes, etc)
I think a legitimate teacher/professor that is reproducing materials for the specific purpose of using it in class is totally exempt from these kinds of things. My wife is allow to copy things, show movies, just about anything at her school.