There is a lot of information that they have to teach in a certain time frame. They can only delay the teaching for so long. If you have a student, or a few students, that don t understand, the teacher still needs to proceed to the next issue. Those students will have to receive extensive help on their own time. Otherwise, the whole class will fall behind on their academics.
Religion is the biggest issue that supports the second principle.
Everyone has his or her own views on religion. No one can fault them for that. Therefore, practicing your own personal beliefs is not appropriate. Also, every one should be respected for their beliefs. I believe the issue of ethics is of greater interest today than it was forty years ago, is because of the change in the society.