Just because something is being used for educational purposes doesn’t mean it’s a “fair use.”
Fair Use allows others to use copyrighted works without the permission of the copyright holder – limited portions, for limited use, for limited purposes.
From Cornell University Legal Information Institute:
17 U.S. Code § 107 - Limitations on exclusive rights: Fair use
Notwithstanding the provisions of sections 106 and 106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include
(1) the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
(2) the nature of the copyrighted work;
(3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
(4) the effect of the use upon the potential market for or value of the copyrighted work.
The fact that a work is unpublished shall not itself bar a finding of fair use if such finding is made upon consideration of all the above factors.
All factors must be considered together. The distinction between fair use and infringement may be unclear and not easily defined. There is no specific number of words, lines, or notes that may safely be taken without permission. It is advisable to use a Fair Use Checklist (PDF – Links to an external source may not be accessible) and keep it on file for future reference. Or, use the Fair Use Evaluator (2008 Michael Brewer & The ALA Office for Information Technology Policy).
NOTE: Acknowledging the source of the copyrighted material does not substitute for obtaining permission.
Watch this 4-minute video from the U.S. Copyright Office (Learning Engine Series) created in 2019.