This site, sponsored by the Kennedy Center, has a ton of resources to engage students in the arts.
BeFunky is a photo editing and creative site that gives you templates of all kinds that you can manipulate and make your own. Then download your creation or share it digitally.
Gimp is an open-source, standalone photo editing software that has been around for many years. It’s about as close to Photoshop as you can get for free.