Please remember as you're finding and using images from the web, that not all are free to use. For your class purposes, you can usually use a variety of images, regardless of image permissions, as your use falls under Fair Use. If you wish to publish or otherwise make publicly available your project for class, you would need to secure proper image permissions.
For more information on image permissions or questions, please contact your Research & Visual Arts Librarian, Anna.
There are many online image repositories that are freely available to access from anywhere, including:
The New York Public Library Digital Collections
The Smithsonian Institution Archives Collections
For more resources on finding images online, please consult the Finding Images Online Guide: