When we are doing technique there comes a time when we "send" uke to the ground by projecting our ki to the ground through what ever part of uke we happen to have a hold on. There are also times when we have uke in a position almost directly under our center (irimi nage comes to mind) where we drop our center ever so slightly to drop uke to the ground. This is, IMHO, dropping ki. How would you describe this to a new student? Would you even bother getting very in depth on this concept with, say, a white belt?