I teach in the automotive feild, but think the problem would be the same in all class rooms. My students have become so attached to their phones that it is a normal thing for them to simply start to use their use there phone at anytime. You have to keep their attention and keep them bussy, or else they start back with their emails, texting, or looking things up on line. This has become the norm in this day and time . Keeping them involed helps keep their mind off the phone. It is said that they want to stay in contact with their family and freinds, but I think it is simply something for them to do to. Keeping their minds on learning is a hard task that we as teachers, instructors, and the like must try and do.