Whenever you reuse free images from the Internet, there are two major considerations to keep in mind:
For example, all Creative Commons (CC) licenses require a base attribution which includes an item's title, source link, author, and license. However, what you are allowed to do with a CC-licensed image depends on its specific license.
You can find more information about CC-licensed works and how to cite them on our Creative Commons Library Guide
If you find a copyrighted image that you want to use in your course, you can make a fair use assessment for that reuse. Remember, your assessment should consider all the factors that your reuse would have on the original creator, and how far your reuse will be shared. If you will only be using an image in your Canvas course with your students, this weighs in favor of a fair use assessment, but it is not the only consideration!
You can find more information about fair use in your course on our Copyright for Research & Teaching Library Guide: