Distracted : why students can't focus and what you can do about it

"A decade ago, James Lang banned cell phones in his classroom. Frustrated by how easily they could sidetrack his students, Lang sought out a distraction-free environment, hoping it would help his students pay attention to his lessons. But after just a few years, Lang gave in. Not only was his no-cellphones policy ineffective (even his best students ignored it), he realized that he, like many of his fellow teachers, was missing an important point....