Fairly early in the semester, I can spot the students who will struggle to complete big assignments, because they are often the same ones who can’t resist the urge to check up on their Facebook friends.

Students’ “on-task behavior” started declining around the two-minute mark as they began responding to arriving texts or checking their Facebook feeds. By the time the 15 minutes were up, they had spent only about 65 percent of the observation period actually doing their schoolwork. —Slate.