I find that the balance ball brings its own particular problem. From the outset I've been told we should actively discourage use of instruments in the formative stages (I know the FAA way is different, but just hear me out please). However, it is very difficult for a student to recognise when an aircraft is out of balance without reference to the ball. How/when do other instructors introduce the balance ball? Do you use it to confirm something (ie set what you feel to be right and then check) or as more of an active instrument? Also, how would you introduce use of the balance ball when entering/leaving a turn? I'm not sure I would want to do it this way. I find I spend a lot of time teaching coordination during Ex4 where I'm trying to get the student to apply the correct amount of rudder against aileron (I demonstrate adverse yaw by 'weaving' the aircraft and then major on how to counter this with rudder). The aim must be for the pilot to sub-consciously apply rudder whenever he applies aileron.
Chuck - in the 172 the amount of rudder used depends on the direction of turn.