I was looking this morning and found this web based animated video creation site. I have been playing with the tool and created a very quick demo of what you can create (the video is not superb, I just wanted to give you an idea of what the program can do).
The animation program allows you to add text, add images (both from the site and uploaded), music (form site or upload own), change backgrounds and upload your own narration. It has existing templates which you can use or you can create your own from scratch. I would recommend using one of the pre-made templates when you start just till you get a little more familiar with the program. I could see students creating some amazing things on here. It does cost to download any videos, however after you create an account you can create wideos and then use the URL to access them.
The site also has some story templates that you can use to plan the animation sequence.
This tool can be used across the curriculum for P-12.
Literacy: create a book title, create a author profile movie, create stories and turn them into videos, use as a procedural text, create a persuasive text etc
Maths: Teach someone about a fact, make a video on shapes, make a video on measurement, survey the class and present the results etc
Humanities: create a video about a historical character, about bugs, how volcanoes work, create a video to share with parents about an excursion etc
General: create videos about the class expectations, about myself etc.