When you use images and audio files for your presentations, you need to respect the intellectual property rights of the original creators of those works. This means using copyright free images, and royalty free audio. The links below can help locate them.
Don't forget the BEST place to look for images, photos, charts, maps, video, audio clips, etc. is in our online subscription databases! Especially, Britannica Image Quest. You will find many curricular-related ones that compliment your research, and each one has the complete MLA citation already formatted! Our subscription gives you license to use them for school projects.
Creative Commons Sharing Creative Works: A Illustrated Primer