These two sites offer good general overviews of copyright as it affects higher education and in-depth explanations of fair use:

This site addresses a number of additional scenarios involving fair use in course management sysytems:

These two checklist can help determine if a specific use falls into either fair use or the TEACH Act:

This chart will explain the complex determination of whether or not a particular work is in the public domain:

When it is determined that permission for a particular use is needed, the Copyright Clearance Center should be the first stop: