Thanks for the info. I am charging about three times what other instructors in the area charge, so I would like to provide more effective training. When I learned about systems in my earlier training days, the instructor explained the sysem on a piece of paper in the back of a hangar. I got an idea of what was going on, but I think I could have got a better understanding at that time if I could have seen the system working. The interactive schematics I have seen in ground schools at a couple airlines and at Flight Safety really increased my understanding of the system, even the most simple systems.