Yeah but if you have it as separate groups then the teacher can't see the work that was submitted while in the original group. Take for example the database activity set to seperate groups. I have a group with a teacher and student. The student writes an entry into the database. Only the teacher of that group can see it. now if I move the student. He can create new entries and the new teacher can see them, but the new teacher can't see the entries that the student wrote when he was in his original group.