Copyright in the Library has evaluations of specific proposals based on the fair use factors. While you cannot rely on this for legal advice, you will see considered opinions given by knowledgeable people, created by the University of Texas.
The Web site, provided by the Stanford Copyright and Fair Use Center, outlines the proposed guidelines discussed during the Patent and Trademark Office's Conference on Fair Use (CONFU).
This tool, created by the ALA Office for Information Technology Policy, helps you evaluate the fair use of a copyrighted work as well as archives the data and process you use to determine fair use.
A non-profit organization that allows flexible copyright licenses for creative works. Check the education section for material you might want to use in class.