I'm teaching an intro character design class this summer. I hate begin one of those teachers who never has any samples - the "can talk the talk, but can't walk the walk". It always annoyed me as a student. While I did have to work on these at the same time my students, at least I did them.
Naturally the first thing to cover (other than being awesome) was thumbnails. I shot for the old 30-ish mark that was drilled into me at CSULB. Hopefully - the kids will walk away with the "process" of drawing rather than trying to get it all right in the first drawing.