I would like everyone to be able to sense what I am building up to before I get to the point where I explicitly spell it out. The trick is to be able to do this in such a way so as to stimulate and maintain the interest of the quicker students, while simultaneously making the lecture understandable and intriguing to those who need a bit more time. Moreover, good teaching must always be a dialogue between the instructor and the class. The communication must be two sided, and not flow in only one direction. The means of dialogue are different in a large lecture, than in a small class, but even in a large lecture, one must elicit constant feedback from the students.
Teaching is dynamic.
It is not static over time. It is for this reason that even though I sometimes teach courses I have taught many times in the past, each time is a unique experience completely different from every other. Math is a very beautiful subject. It is sweepingly powerful and charmingly graceful at the same time. It is more an art than it is a science, although unfortunately it is an art that is feared by too many and appreciated by all too few.