Nate Anderson has an interesting piece on the lack of understanding among teachers of fair use
link here. Researchers wanted to know if confusion over using copyrighted material in the classroom was affecting teachers' attempts to train students to be critical of media
link here. The answer was "yes." The study, by the Center for Social Media at American University cites fear of law suits, lack of understanding of the vague rules for fair use, and a desire to avoid controversy.
One example: a teacher had his students create mashups of pop music and news clips to comment on the world around them. The school refused to show them on the school's closed-circuit TV system because "it might be a copyright violation."
Is there a good short clear guide to fair use? Fair use gets 1.7 million Google entries, so there seems to be a need for greater clarity.
Fair use is the excuse a court may use if it chooses to be merciful.
A school has a choice to ignore copyright (as it should) and let itself be sued into oblivion as a martyr, or to avoid all potential infringement and let society wail at the poor education of their students and their school's cultural vacuity.
The point is, the fair use exemption occurs (if at all) long after extortionate litigation. It is not to be considered when determining a "Shall we, or shan't we, infringe copyright as a matter of course in this school?" policy.