Within the classroom, there is a pretty broad exception for using copyrighted materials (not quite everything goes, but broad). It applies to “face-to-face teaching activities”—those that happen in the actual classroom. Can we use this same exception for online classes? In a word, no. But, there is another exception, called the TEACH Act [sections 110(2) and 112(f)], designed specifically to deal with online distance learning. Because the digital environment poses unique challenges for copyright, particularly the ease with which digital material can be copied and distributed, the law imposes a number of requirements on distance learning that do not apply to face-to-face teaching.
The Fair Use Doctrine is a case law doctrine which says that it is not copyright infringement if the user is using the material for a "fair use". The only way to get an absolute answer as to whether a use is fair is to have it resolved in court. Judges use the following four factors to determine fair use: