What is the main subject of this talk?

Good afternoon, and I’d like to welcome you all to Physics 101. This is not an easy class, and I want to inform you of my rules before I begin. Let’s take care of administrative matters before we move on to scientific matters.
     First of all, let’s talk about the attendance policy. While I have no stern policy regarding attendance, I consider it to be the most important aspect of being a student in my class. I passed out an outline listing readings you must do before class. It is important to keep up with the week’s readings because your lab will be based on it. If you miss more than four class sessions, l am obligated to give your name to the Dean of Students and you must meet with the Dean. If the Dean feels your absences are inexcusable, you may receive a failing mark for this course.
     A missed lab will count as two missed class sessions. I feel that labs are doubly important and hence, I give them double value. If you miss a quiz or a test, you can schedule a make-up during my office hours from four to five o’clock on Monday through Friday. Because I have office hours five days a week, this gives you plenty of time to see me. So I have a strict policy that you must make up exams within three days.