Educational Uses of Non-coursepack Materials (fairuse.stanford.edu)
Example of what can be copied and distributed in class would be a complete article, story, or essay if less than 2,500 words, but not more than three from the same collective work or periodical volume during one class term.
The idea to make the copies must come from the teacher, not from school administrators or other higher authority. Only nine instances of such copying for one course during one school term are permitted. In addition, the idea to make copies and their actual classroom use must be so close together in time that it would be unreasonable to expect a timely reply to a permission request.