for me, the use of the phone in class first is a breach of the school rules, and lack of respect for the sanctity of the place,as it's a full confusion for students who want to concentrate during the lesson,also it's a kind of lure for the user to not be able to focus on the explanation of the prof, and that's gonna be a big reason for getting low marks,but using it only for some difficulties of study and only for some minits could be useful sometimes.