Fotoflexer bills itself as the most advanced online photo editor. I would have a hard time disagreeing. FotoFlexer is a fun, kid friendly online browser based photo editor with a user friendly interface. The site costs nothing to use and you do not even have to sign up for an account. I enjoy the site because it is very easy for my students to load up their images and apply dozens of effects, crop, resize, mirror, flip, rotate, etc. then save as a jpg file back to my computer. It even has a very handy and convenient UNDO button so students can practice trial and error on their images till they get them exactly right.
Here are some examples of the tools you can use in FotoFlexer:
I know there are other sites that may offer similar features, however, FotoFlexer is another tool to add to your teacher technology toolbox. My students love it and I am sure yours will too. Below, I have posted several examples of some of the editing I did on my school picture.
Check out FotoFlexer: