I have a seating chart for all my classes, but when they're working on their own, I let the kids move around and work next to their friends if they like. I tell them they have to be back in their normal seats when we discuss something as a class. I have found this to be a nice arrangement, but my head of school came in to observe and he recommended that I tell them where to sit. He said letting them choose has an impact on productivity, though he never got more specific than that. I should clarify that if they're doing an assessment in groups, then I choose groups while accepting advice from the kids about my choices, and I explicitly teach group work skills. When they move around and sit where they like, they are working on individual assessments. Do you think I should continue with my current arrangement, or follow the head's advice? I could continue with my current arrangement without getting into trouble, since the observations are very infrequent and I'm in good standing with management.