msclause:

I think as long as a student, or person, has the phone on silent, he/she is not disturbing anyone. It is their choice if they should concentrate in their class (its their choice to be there in the end, no?) or in the conversation.

You are too young to be more than just barely in college so you must be talking about high school. And I do believe it is the law that kids be in school during the school day - it isn't their choice at all. In the same way, to the best of adult's abilities, it isn't their choice if they pay attention or not either.

Why? Kids are little id driven creatures. You don't allow them choices on what is best for them or by the time they are adults they will be to screwed up to function in society.

What people do with their friends is up to them. Cell phones in school should have a special holding box by the door - pick it up in an emergency but otherwise kids don't need to have them.