Fair Use is a doctrine within U.S. copyright law that allows for some limited use of of copyrighted material without the permission of the copyright holder. The circumstances under which fair use may apply include criticism, comment, news reporting, teaching, scholarship, and research. Four tests are involved: purpose and character of use, nature of copyrighted work, amount and substantiality of portion used, effect of use on potential market for copyrighted work.
According to Section 107 of the Copyright Act ". . . for purpses such as criticism, comment, news reporting, teaching (including multiple uses for classroom use), scholarship, or research is not an infringement of copyright." Subject to the following four factors:
Fair use is about balancing of the 4 factors
Not all educational use is fair use.
Using rules of thumb like certain percentages or numbers of words is not actually protected - it is a better idea to use only as much as necessary to get your point across and not rely on certain numbers or percentages
The 4th factor may not be the most important factor, but it is an incredibly important one
Some questions to ask that may help in determing whether a use is "fair use" would include"
“Transformative” uses refer to the first factor and are looking for whether
Transformative uses are more likely a Fair Use
Some Questions to ask when assessing whether your use is tranformative: