Two exceptions, found in section 110(1) & (2) of the Copyright Act, apply specifically to teaching activities. These are both exceptions to one of the exclusive rights held by a copyright owner, the right to authorize public performances of the copyrighted work. Public performances happen all the time in teaching, whenever a poem is read, a play staged or a film screened for students. All of these performances would be considered public, even when confined to a small class of students, under the broad definition in the copyright act. So a specific exception to the public performance right is included as section 110(1), which allows public performances without permission as part of face-to-face teaching activities of a non-profit educational institution, in a classroom “or similar place devoted to instruction.” The only further requirement to benefit from this exception is that the copy of a film or other audio-visual work that is performed must be legally made. Copies that are purchased from a reputable vendor or borrowed from a library, a friend or a video-rental service are all lawfully made.
The other teaching exception in 110 is the TEACH Act, which greatly expanded the opportunity in subsection (2) for performances via distance education. Unlike subsection (1), the TEACH Act is full of specific requirements to enjoy its benefit. Some of these requirements are rather difficult for many institutions to fulfill; the best summary of how to interpret and use the TEACH Act is found in this TEACH Act toolkit from North Carolina State University.
Because these exceptions are so specific and, in the case of the TEACH Act, so difficult to use, many educational activities have to rely on fair use — the broadest exception in US law to the rights of a copyright holder — if they are to proceed without seeking permission.