In my classroom, every student has a laptop. Now a days, they also have smart phones which have internet access. During my lectures, and anytime I am speaking I have them all close their laptops and leave their phones in their bookbags. Walking through the school one day I peaked through the window of another intructors room and saw that he was lecturing and all of the laptops were open to Facebook, Yahoo, whatever. During lunch, I took him to the side to tell him this, and he was surprised to hear about it. He made a point to have all of them close them from then on and noticed an improvement in grades. : )