Joining a class that would run over several weeks that would teach his improvisational writing and rehearsal technique used by Mike Leigh I found that the class would watch as a direct, three actors and a write did exactly this. We didn't get to improvise - I enjoyed acting at the time. We didn't get to work with the actors - I wasn't so much into directing yet. And we didn't even write. This was meant to inform our own projects. I didn't. I found it hugely frustrating to be watching others do stuff, have fun and learn from the experience, while we in the 'class' were meant to pick it up from a chair at a distance. All we were taught was how, through demonstration, to run an improvisational session.
LESSON > if you aim is to teach someone to do something, have them do it not sit on the sidelines.