The Classroom Exemption Act

Section 110 of the Copyright Act, sometimes called the “classroom exemption” act is a public performance/public show restriction, which provides exemptions on the exclusive rights of copyright holders. These exemptions allow educators and students to perform and display copyrighted works within the classroom. Note that this exemption applies to classrooms only, not the Internet. Face-to-face instruction is the only place where non-profit educational institutions can show movies or other audio-visual digital works.

UPDATE: The TEACH act repealed Section 102(2), meaning that restrictions on what can be put on the web or internet have been loosened.  See the TEACH Act for more information.