How do I use potentially copyrighted images in my course material? I teach at a school and I create PowerPoint presentations to use in my classroom.  I also need to upload the PowerPoints to my school website for my students to access.  Access is restricted and students must sign in with their school codes.  Can I use images I find on Google search?  Are all images copyrighted?  If they do not have an "ownership" stamp on them, are they ok to use in this manner?  Nothing is being sold and the presentations are taken down at the end of each year.
Images found in Google search don't belong to Google.

I can't speak to fair-use under academia, but I can say images aren't fair game just because they're found on Google images

There are, however, places you can find images you can use. Wikimedia has a ton of images that can be used, with a wide variety of licenses for re-use. Flickr is another that comes to mind.

I want to reiterate that I don't know fair use under the realm of academia, but would ask permission and highly recommend captioning photos in order to give credit where it's due.