Much of what happens in the classroom requires teachers and students to copy, display, and perform copyrighted works in order to learn. Fortunately, there are some specific provisions to the copyright law that allow teachers and students to use copyrighted works in specific ways.
This exception, in 17 U.S.C. Section 110 of the Copyright Law, states the following is allowed: "performance or display of a work by instructors or pupils in the course of face-to-face teaching activities of a nonprofit educational institution, in a classroom or similar place devoted to instruction, unless, in the case of a motion picture or other audiovisual work, the performance, or display of individual images, is given by means of a copy that was not lawfully made under this title, and that the person responsible for the performance knew or had reason to believe was not lawfully made . . .."
Note that this exception only allows for the performance or display of a copyrighted work, and it in no way influences the requirements of academic integrity (so citing sources should still be encouraged). This part of the law only applies to face-to-face teaching. For online teaching, the TEACH Act is meant to provide guidance for what can legally be done in instruction. This law, unfortunately, has many requirements and it can be difficult to comply. More information about what activities are allowed and under what circumstances are found in Section 110 of the law. In many cases, it may be more productive to rely on fair use in online teaching environments (see the Fair Use tab).