In case you are interested, there is a curriculum that ScratchEd team has developed. http://scratched.media.mit.edu/resources/scratch-curriculum-...
Personally, I also "wing it". I encourage them to come up with ideas for games, animations that implicitly requires them to cover all aspects of "computational thinking". It's implicitly because I don't want them to think of this as too academic; let them have fun while learning (for a change!)
Looks interesting -- they posted that a week or two after I was searching. We're heavily into animations and games right now, including one where the student is building up space invaders, one complication at a time.
