1. MYTH: If it doesn't have a copyright symbol, it's not copyrighted.
REALITY: Many published works contain a copyright notice, but many don't. For works published on or after March 1, 1989, a copyright notice is optional. The fact that a work doesn't have a copyright notice doesn't mean that the work is not protected by copyright.
2. MYTH: It's okay to use someone else's copyrighted work as long as I provide a citation.
REALITY: Citing someone is not the same as getting permission. If your use doesn't fall within the provisions of one of the educational exemptions or isn't a fair use, you need to either request permission or not make use of the work.
3. MYTH: I can use anything I find online because content found on the Internet isn't copyrighted.
4. MYTH: If I only use a small amount, I don't need to ask permission.
REALITY: While using only a small amount of a copyrighted work may be fair, you need to consider other factors before making use of even a small portion of a work. There are really no "bright lines" (numerical amounts) that can keep you within a safe harbor when using someone else's work. If your use doesn't fall within the provisions of one of the educational exemptions or isn't a fair use, you need to either request permission or not make use of the work.
5. MYTH: I'll be safe if I change the work by [fill in percentage here].
REALITY: Nothing in copyright law indicates that changing the material by a certain percentage will protect you from copyright infringement. In fact, making derivatives is one of the rights a copyright holder enjoys. You cannot claim copyright to someone else's work no matter how much you change it.
6. MYTH: Using copyrighted materials is always okay if my use is educational.
REALITY: Many uses of copyrighted material in the non-profit educational environment are fair, and there are special exemptions for educational uses, but just because your use is educational does not automatically give you permission to copy and distribute other people's work. If your use doesn't fall within the provisions of one of the educational exemptions or isn't a fair use, you either need to request permission or not make use of the work. Educators should always be very careful when using commercial materials that are designed for, and marketed to, an educational audience.