If the teacher combines the third stage of the action that has taken place in the classroom with the fourth stage which is the recapitulation and the discussion, then he can specialize in specific issues of the subject. In our example with the trial of Galileo, Galileo’s arguments may have gone as far as proving that the earth moves. But the teacher may also specify that the earth moves around the sun in an elliptical orbit. Because of this orbit, in a year the earth moves away or approaches the sun in a specific way. In this way, in the northern hemisphere, we have winter while at the same time in the south we have summer.