Using images for educational purposes is allowed under fair use exemptions to U.S. copyright (U.S. Code, Title 17, Chapter 1, Section 107.) Use of a copyrighted work for criticism, comment, news reporting, teaching, scholarship, and research are not considered infringements if the use weighs favorably when considering these four factors:
Generally speaking, using copyrighted images for teaching and education is considered fair use. However, if that includes posting images to a website, that could be considered a publication and therefore copyright infringement.
Fair use is not always clear and must be decided on a case-by-case basis using the four factors listed above.
When citing any source used in a project or paper, proper attribution should be provided for any images. Each discipline has slightly different requirements, so be aware of what is required.
The basic information should always include:
The Library does not recommend uploading PDFs to Canvas. Material available through the Library (like the full text of an article accessed through an electronic database) is subject to the terms of individual licenses with publishers, which may or may not allow this kind of use. Even if it is allowed by the license, material should not “live” on Canvas indefinitely. Access to the material should be terminated by the end of the semester. Additionally, if there are changes in the future and the Library no longer provides access to this article, the continued existence of the PDF on Canvas would definitively be a violation of copyright.
Therefore, it is best—and easiest—to link to material, rather than upload material. This way you do not have to worry about licenses or manual removal of material at the end of a semester.
There are two main sources of content for which you don't have to worry about copyright clearance: public domain works, and works whose licenses allow your use. Find sites for free images.
Fair use is designed to be flexible, and courts have resisted applying specific numbers. Fair use determinations must weigh all four factors. In instances of particularly transformative uses, such as parodies, someone might borrow far more than 10%. 10% is a conservative number found in many best practice documents relating to academic copying.