According to the Copyright Society of the USA, "Copyright is a form of protection given to the authors or creators of ‘original works of authorship,’ including literary, dramatic, musical, artistic and other intellectual works."
In general, it is illegal to do the following to copyrighted works without first obtaining a license:
Make or distribute copies
Publicly perform the work
Publicly display the work
Make “derivative works”
Works in the public domain are not protected by intellectual property laws. Anyone may use these works, no license or fee required!
Usually, works enter into the public domain because:
The copyright has expired
The author consented to the release of the work into the public domain.
The copyright was not renewed properly.
The item in question is not protected by copyright (i.e. government documents, short quotes, ideas, etc.)
General rule: As of 2021, if it was published in the U.S. before 1926, it’s in the public domain. For all other works, check, but don't count on it.
Reference Cornell University Library's copyright term guide for detailed information on when works enter into the public domain.
Movies:
https://publicdomainmovies.info/
Internet Archive (also contains books and multimedia sources)
Books:
Google Books (search works published prior to 1926)
Pictures:
Google Images (set usage rights to "creative commons")
Music:
Public Domain Information Project
IMSLP (Petrucci Music Library)
Historic American Sheet Music (Duke University)
For more information, see Stanford University Libraries' guide to the public domain.
Yes, sometimes! Fair use and face-to-face teaching exceptions may apply.
Under 17 U.S. Code § 107, fair use doctrine permits limited, unlicensed use of copyrighted materials, for purposes such as teaching, scholarship, research, criticism, or news reporting.
To determine if "fair use" might apply to a given situation, considering the following four factors:
Purpose and character of use: Is the work being used for non-profit educational purposes? Is it being used for teaching, criticism, scholarship, research, or news reporting? If so, it is more likely to be fair use. Additionally, courts tend to favor uses that are "transformative," rather than mere reproductions.
Nature of copyrighted work: The use of non-creative, non-fiction works is more likely to be fair use than highly creative works like music or poetry. Fair use is also more likely to apply to published works than unpublished works. Additionally, use of work that is commercially available specifically for the educational market is unlikely to be fair use.
Amount of work used: The more you use, the less likely you are to be within fair use. See the link below from the Xavier University Library for frequently-referenced guidance on how much of a work to use, but remember, fair use is all relative and measured in qualitative terms. Never use more than you need, and be cautious of using excerpts that encapsulate the "heart of the work" or the most creative elements.
Effect of the use on potential for or value of the work: Will your use of the materials have an adverse effect on the market or harm the original copyright owner? In other words, to what extent are you undermining the sales or need for the original work?
The following chart provides guidance on how much of a work may be used under "fair use":
General guidelines for fair use of copyrighted materials (Xavier University Library)
Note: Many of these guidelines derive from a 1976 agreement reached among representatives of the Ad Hoc Committee of Educational Institutions and Organizations on Copyright Law Revision, the Authors League of America, Inc., and the Association of American Publishers, Inc. following several Judicial Subcommittee Meetings in 1975. Representatives of the three organizations recommended these guidelines to Congressman Robert Kastenmeier for permissible use of copyrighted materials under "fair use." That being said, these are not legally codified limits - these are recommendations. More or less may be permissible in different situations.
The following resources can help you evaluate if "fair use" might apply to a given situation:
Columbia University Libraries fair use checklist
American Library Association fair use evaluator
Reproduction of Copyrighted Works by Educators and Librarians (U.S. Copyright Office)
Please note, fair use is a legal defense used in court after copyright law has been broken. Only courts can truly determine if "fair use" applies, so the less copyrighted materials used, the better. Whenever possible, look for alternatives, such as putting high-demand books on reserve in the library, rather than making copies.
17 U.S.C. Section 110 allows for the "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."
In other words, if the material is lawfully obtained, you may generally perform or display the following copyrighted materials to your enrolled students in a face-to-face classroom setting, provided that the work is directly tied to your instruction:
An image
A video, such as a movie
Print text
Music
The following guides provide further information:
University of Illinois Library guide to classroom-use exemption
Purdue University Copyright Office guide to face-to-face instruction
Please note, performing or displaying copyrighted materials purely for entertainment purposes in school is unacceptable, even in a classroom setting. For example, showing a movie for entertainment during lunch or at an after-school club meeting is a violation of copyright law. To legally perform or display copyrighted materials for entertainment purposes, the school would need to obtain a license.