According to Wikipedia:

Open content, a neologism coined by analogy with "open source", describes any kind of creative work published in a format that explicitly allows copying and modifying of its information by anyone, not exclusively by a closed organization, firm or individual.

Copyright – symbolized "©" – is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time.

http://en.wikipedia.org/wiki/Copyright

Chilling Effects-- Copyright and Fair Use

A Teacher's Guide to Fairuse and Copyright - very thorough webpage - check out the chart for educators... good quick look at copyright use in the classroom.

http://home.earthlink.net/~cnew/research.htm#Fair%20Use%20Matrix%20for%20Teachers

Copyright 101 for Educators: Winter 2003: (Published in the TechEdge 2002-03) by Wesley A. Fryer

"Copyright and Fair Use in the Classroom, on the Internet, and the World Wide Web" by the Library and Information Services division of the University of Maryland University College (www.umuc.edu/library/copy.html.

United States Copyright Offices--- Copyright Basics

Great chart with comparisons...

Overview and resources for copyright and fair use guidelines: Stanford University Libraries

http://fairuse.stanford.edu/Copyright_and_Fair_Use_Overview/index.html

Another chart with examples:

http://www.copyright.cornell.edu/public_domain/

The Learning Center is designed to help educators and students develop a better sense of what plagiarism means in the information age, and to teach the planning, organizational, and citation skills essential for producing quality writing and research.

http://www.plagiarism.org/

Another Great chart:

http://www.copyright.cornell.edu/public_domain/

Take a Copyright Crash Course on the University of Texas website.

Specific to online learning:

The TEACH Act facilitates and enables the performance and display of copyrighted materials for distance education by accredited, non-profit educational institutions (and some government entities) that meet the Act's qualifying requirements. Learn the basic facts...

Visit Copyright Bay and learn what you need to know to stay within the law concerning copyright, fair use, and public domain. Then take the 

Shakedown Cruise to see where you stand in your knowledge!