If you or your students are looking for images, sounds, audio and videos that can be legally used in projects, try Creative Commons Search
Search by usage rights, or website hosts.
Please note, however, CCSearch is not a search engine. It provides access to other search engines that will search for creative commons license materials. Always verify that the returned results are covered under CC license terms. If in doubt, contact the copyright holder or the site where the content was found. (Image by oddsock flickr)