These resources are subject to change. It is always possible that a copyright owner will take them out of circulation or that links may break. You can find Open Access resources but using the following links or by using a search engine such as Google.
OA is important for you as a student because it means that you don't have to pay for the resources you use. It's important to your instructor because it means they can use resources that you access from inside your Canvas Course. Because they are OA, they are the same quality resources as the ones you find in the library databases. In fact, you can find your own OA resources for your papers by following these instructions:
There are some databases that require subscriptions but that do have some Open Access materials.