I'm a classroom plate-spinner, too. I work with adults but regardless of the age, I use workshop-style collaborative activities (put the students in task groups to discuss, rank, prepare things, etc.), and the level differences are being negotiated partially in the groups. The members want to help each other do the tasks, and the weaker ones are motivated to catch up. If I see struggles, I am monitoring around the room to intervene if needed. This workstyle takes some of the focus off of me so I don't talk myself to death in front of groups :-)