Fair Use does not equal a "free pass."
Fair Use allows the use of portions of copyrighted creative work in educational settings without first obtaining permission for the purpose of criticism, comment, news reporting, teaching, scholarship, and research.
Answer these four questions to see if fair use applies:
Copying by instructors must meet the tests of brevity and spontaneity. Brevity refers to how much of a work you can copy. Some practitioners claim that 10% of a work is acceptable, but there is no set percentage that is legally considered an acceptable amount to copy for fair use. All uses should be evaluated individually. Spontaneity refers to how many times you can copy. Frequently an instructor may use a work for one semester within a fair use context. Using a work repeatedly, semester after semester, in not spontaneous and no longer falls within fair use.
Check out these sites which provide real-life scenarios involving copyright uses in the classroom: