(f) (f)reeze/unfreeze rotation
(t) start/stop (t)eacher
(s) start/stop (s)tudent
(0) main camera
(1) teacher shoulder
(2) teacher upper arm
(3) teacher lower arm
(4) student shoulder
(5) student upper arm
(6) student lower arm
(v + 1-6) view from joints
(c + 1) place camera center on student
(c + 2) place camera center on teacher