You should never post the entirety of a copyrighted work (articles, images, video, audio) on a public website (available to the world) without first asking permission of the copyright holder. You may, however, be able to post an excerpt if it constitutes a fair use or is not an infringement under another exception under copyright law.
Under certain circumstances (see below), it may be permissible to post copyrighted material to a closed website (e.g. a course site limited only to students in the class).
The TEACH Act provides a “safe harbor” against infringement for certain online educational transmission and exempts uses “in the course of face-to-face teaching activities…in a classroom or similar place devoted to instruction." The TEACH Act includes a series of requirements for educational use including
There can be civil or criminal penalties for faculty, students or relevant staff. There also can be injunctions issued (i.e., court orders to stop doing an activity, like posting infringing materials.) In general, if someone is found guilty of infringing a copyright, the court can award statutory damages between $750 and $30,000 for each infringement of each work. If the court finds an infringement was willful, the court may increase the damages for each infringement to up to $150,000. If a court finds that an infringer was not aware and had no reason to believe that his or her acts constituted a copyright infringement, the court may reduce the damages to as low as $200 per infringement. Importantly, a court can refuse to award statutory damages at all when library personnel are making photocopies as part of their employment, and believed, and had reasonable grounds to believe, that the copying was a fair use. See 17 USC 504(c)(2)(i).
In order to utilize the teach act the following conditions must be met:
Instructors who scan and mount their own electronic readings should include a copyright statement at the beginning of each protected document. The library uses the text below:
The copyright law of the United States (Title 17, United States Code) governs the making of photocopies or other reproduction of copyrighted material.
Under certain conditions specified in the law, libraries and archives are authorized to furnish a photocopy or other reproduction. One of these specified conditions is that the photocopy or reproduction is not to be used for any purpose other than private study, scholarship, or research. If electronic transmission of reserve materials is used for purposes in excess of what constitutes "fair use," that user may be liable for copyright infringement.
For those who are using Coursera (https://www.coursera.org/), the massive open online courseware (MOOC) used by Penn and many other universities, there are special copyright considerations.