Yes, as long as it is for educational purposes, showing clips or excerpts is allowed under fair use according to the U.S. copyright law in and outside of the classroom.
Consider these four factors when determining if your purpose is fair use:
- Purpose and Character of the Use
- Is your use of a commercial nature or is it for nonprofit educational purposes?
- Fair use favors nonprofit educational purposes.
- Nature of the Copyrighted Work
- Is it factual or creative?
- Fair use favors work that is factual.
- Amount and Substantiality of the Portion Used
- The larger the amount of the content that is shown, the less likely it will be considered fair use.
- Effect of the Use Upon the Potential Market
- What is the value of the copyrighted work?
- Does your showing have a significant impact on the profits of the copyright holder?