One of my favourite digital activities in the classroom is digital storytelling. What I like so much it is, that it fosters creativity as well as media literacy and IT skills among the students. Of course it also provides a big challange for the teacher. Very often there is not much time to demonstrate sophisticated animation software, so you have to rely on very simple tools and make the most out of them. Movie Maker, Photostory and animoto are only a few of the most popular tools. You can also choose PowerPoint or from quite a lot of web 2.0 services (such as powtoon, prezi and go!animate) and record your animation with a screenrecorder (e.g. screencast-o-matic).
Basically, you can screencrecord almost anything that is animated on the web. Animated charts or maps might be one idea. Check out this posts about using Google Maps for animation projects.
For more sophisticated animations you require software that allows keyframing, such as Premiere (Elements), Flash or After Effects (you can get demo versions of all of them). Premiere is probably the easiest way to learn keyframe animation, but its also very limited. Another quick way of doing animation is the puppet tool in After Effects.
You get examples from most of these tools in this video which I have created from diverse school projects.