I'd definitely not make it too theoretical (when I did, I had really bad experiences, even when people attending to the classes were college students). The best way to go is somewhat the 'easiest'. Make it simple, fun, practical and I'd also suggest to focus a lot in iconic pixel art. It's also good to show a LOT of references. Regarding practical taks, they could start with small images such as a 16x16 favicon and then go for a portrait and a small character sprite (4 frames, for example), that would be a good introduction to pixel art, to its iconicity and animation, respectively. 2 hours per classes would be pretty nice.
It would also be awesome if you could post a summary of your experiences and what called your attention most, what you would include and what you would exclude from your classes.