Marco, I'll tell you, having a good lesson prepared with all needed resources readied makes such a difference in terms of having the classes run smoothly, students more attentive, and the instructor comfortable with the presentation and delivery of course material. I don't think many could just breeze in and teach a class without that needed preparation. Well organized instructorss demonstrate their competence by knowing beforehand what topics they will discuss and what supporting resorces they will need. Barry Westling