I understand students' annoyance with the harsh disciplinary rules of school. I am well aware that each works very hard, and you are ambitious students. And yes, sometimes we are late, or not prepared due to unforeseen circumstances.
Let me try to explain the reasons why the school has made these disciplinary rules. First, a student will not be expelled for being late in the morning, where traffic and other things can hinder us all in getting to our destination on time. If a student is late in the morning, all that happens is that our receptionist calls the student's home, to inquire whether he/she is ill, or on his/her way to school. The reason why the school does this is that last year students would pretend to go to school, but not show up. We are all well aware that sometimes students or teachers will be late.
This leads me to explain why the rules have been imposed: They relate to subject teaching, where the individual teachers prepare the students to pass the IB-Diploma exams.
The IB Diploma is very challenging, for students as well as teachers. Last year we were in the situation, that up to 75% of the students in grade 11's class would come to class without books, notebooks, and without being prepared. Besides the lessons themselves being impossible for teachers to conduct on a sufficient level, it led to diligent students loosing their desire for preparation, for why prepare, if it did not make any difference? It was a general occurrence in all their classes, but I can say that for history, most went from a grade of 80% to a grade of around 60-65% as a result of other students not doing their work.
Besides, students would be 5 - 10 even 20 minutes...