I came accross Automatoon today and have spent about 15 minutes on it with my kids and the best thing I can say about it is that it is definitely kid friendly and something they can use right now to get creative in your classroom.
Automatoon is completely web based and free. There's no fussy authoring software to install (or pay for!) and you can effortlessly share your animations online. You can also easily export your animations and embed them in your own websites, all for free!
Automatoon is the easiest animation tool ever created. It is built using a new technology called CBT or "Composition by Tool". CBT is an algorithm that changes how the data behind an animation is structured, greatly reducing the effort required to create it.
Automatoon is powerful. Automatoon has many advanced animation tools built in, including skeletal animation, inverse kinematics, automatic tweening, morphing, and fades. More importantly, in Automatoon you can actually figure out how to use these tools without spending hours with a manual- CBT makes them completely intuitive.