I like having your class. They are self-propelled.
Self-propelled may be just the term to describe what I want my class to be - especially when a substitute takes over. I like the idea that my class can work independently, relieving much of the substitute's responsibilities. Not only will the work being completed be more of the style that I would like students to complete, but the substitute is freer to monitor for difficult behaviors and students who need more attention academically.