Splashup is a great little photo / image editor that works straight from the browser. It is really user friendly and will easily be handled by students and novices alike but it also has some depth to it. For example photoshop users will be impressed to see that you can use layers which puts it above many basic / free image editors that are available out there.
It links into all the major web based photo sharing services such as Picasa, Flickr Etc and has a range of dynamic brushes and filters.
All in all this is definitely one of the best free Photoshop alternatives for beginners I have seen and would definitely solve most beginners problems easily right from the browser. This program would be great for students earning their graphic design degree online too. Check it out here.