Fair use allows certain uses of copyrighted material without permission from the copyright holder. There are four factors to consider when determining whether your use is a fair one. You must consider all the factors, but not all the factors have to favor fair use for the use to be fair.
The four fair use factors are
Fair use favors “purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, [and] research.” While many uses for educational purposes are fair, not all are. You need to evaluate your use each time you are reproducing copyrighted material — to include in a presentation, to include in your writing, or to post on your course website.
Fair use is codified at 17 U.S.C. § 107.
Because images are so often published without attribution, it can be especially difficult to locate their copyright holders. This can also make it difficult to cite images properly.
If you have an image you would like to use or license but need to identify and contact the copyright holder, a reverse image search engine may be helpful. You can use a reverse image search engine to find out where an image came from, where it is being used, and whether higher resolution or modified versions of the image exist.
If the image you want to include in your work does not have a Creative Commons license or is not in the public domain, you should contact the copyright holder to get permission to use their work, especially if your work is going to be published for commercial purposes. However, if your use of the image falls under the conditions of Fair Use, you do not need to seek permission; most student work will not need permissions.
Permissions, a Survival Guide by 
University of Michigan-Flint