Automatoon is a great Web 2 tool to use in the classroom for free. There's no authoring software to install and you can share your animations online. You can also export your animations and embed them in your own websites (e.g. classroom blogs), all for free! These could also be used in other web 2 tools such as Glogster or 280 slides. What a great tool to use as a reading activity for example - certainly would give motivation for some readers. I used animation in my classroom as a reading activity where the children designed an activity (simple) that one of the characters from the story was likely to do. They could then make the animation for others in the group to guess who it is and what they are doing.
This video shows you how to use it.