Third grade test pilots

I tried out my idea for a collaborative Scratch project, using the third graders as guinea pigs. This was our initial result:
The kids worked in the desktop version of Scratch. I uploaded their projects to the beta site and saved all the sprites in the new backpack feature.

What I liked: I really like the backpack and can see it as a very useful feature, but what I didn't like was that when I uploaded a new project tp grab the sprite, it replaces the old one. SO all the uploading of sprites seems to have to take place at once... or I have to save each iteration. I think probably saving each iteration makes more sense, but is something I need to play around with.
The kids had no trouble at all doing this in one 40 minute period. They made the sprites, with a minimum of 3 costume changes for the animation. I had written a short script to make them dance, but many students made changes to this. The whole concept seemed to make sense to them.

I pulled background images from wikimedia commons of places in the area. This class is familiar with all of these places from their Berkshire diorama projects. I pulled the song for the background from a piece the kids did with Responsive Classroom and their music teacher.

So.. how can this work with other classes? I would envision an initial handshake similar to this project to introduce the classes, then each student could do their own animation as an individual handshake. The classes could work in groups, similar to the current AWL project, but the medium to present would be scratch... background images from photos and a walking , talking sprite to convery the comments.

Still not sure of a lot of details-but liked some of what I did on this so far.