A copyright ensures that any published material, whether it is visual, audio, or text, is protected against plagiarism. The purpose is to ensure that the creator of said material is the sole beneficiary of any financial gain related to the material. This means we cannot show a film to our classes without purchasing it, or borrow a book form the library and photocopy the pages to distribute to students to avoid buying a class set. Copyrights are protected by the US Constitution, so getting on the wrong side of a copyright dispute can land someone in court. This law also protects teacher created materials that are published on marketplace websites to sell.

Fair Use is an exemption for education, meaning if you are using copyrighted material in a class project, not-for profit, and do not intend to use it beyond the walls of your classroom, it is generally not going to violate copyright laws. So if you want to play a popular song during a slide show, that's fine, but if you want to publish it to YouTube, you may run into a problem. Basically, Fair Use allows you to utilize copyrighted work, as long as the owner will not suffer financially as a result. This may allow you to use small portions of a copyrighted work (such as a short film clip), but not the work in its entirety provided that:

1) The use occurs in person for educational purposes

2) the original content was obtained lawfully or is covered under fair use. (no bootlegs)

When using a work under the protection of Fair Use, a citation is not required, though it's certainly polite.

Anything that is considered public domain is free for use and reproduction in the classroom. Public domain includes any item that has never been protected by copyright, cannot be protected by copyright, or is no longer protected by copyright. Works created before the establishment of copyright laws in 1923 are all considered public domain. Works published afterword are protected anywhere from 67-120 years depending on a variety of factors. This is why it's okay to use founding governmental documents (such as The Constitution) without citing your source. Although it would be difficult to replicate and Ansel Adams photo, you are free to attempt to do so because the scenery that he photographed is public domain. Ideas, scenery, facts, recipes, and fashion designs are all examples of items that are not covered by copyright laws.

This video provides an explanation of how copyright and fair use can potentially impact your use of media in your own teaching practice. If you want to use something that is copyrighted in the classroom, and your purpose does not fall under fair use, all is not lost. It is possible to obtain permission directly from the creator of the work. It's always best to play it safe and avoid copyright infringement.