College students seem unable to get off their cellphones . Professors find it challenging to get students to stop using their cellphones in class. Doug Duncan, a professor at the Universit y of Colorado has come up with a solution to smartphone distraction in his astronomy class . He has published a paper showing that, at his college, more than 75 percent of undergrads reported texting while in class, and that in class texting was linked to an average drop of half a letter grade in the course. T en percent of the grade in Duncan's class comes from participation points. To reduce smartphone use, he carried out an experiment. While sharing his plan with his colleagues , he wrote: “ I asked my students to vote ( 投票表决 ) if I should offer one participation point for taking out their cellphone , turning it of f and l eaving it out o n my desk. To my amazement 100% voted yes. So they all took out their phones, put them on the desk, and we had an extremely engaged class. ” Three class meetings later, the no-cellphone rule is still going strong. Should other professors follow Duncan's lead? Larry Rosen, a research psychologist at California State University, studies smartphone use among college students. He doesn ’ t think simply rewarding students for turning off their phones is a good strategy. “ It doesn ’ t get at the real issue of why students are distracted, ” he explains. “ Most college students are heavy users who are going to get anxious within 10 or 15 minutes if they can't check their phones. ” In experiments, Rosen has shown that students ’ heart rate and other vital signs( 生命体征 ) rise when they hear their phones ring and can ’ t answer them. He says that putting the phones in sight, but out of reach, even when turned off, will only increase that anxiety and the distraction that comes with it. Rosen has his own solution. “ I start by calling a tech break, where they can check their phone for one minute, every 15 minutes, ” he says. “ Over time you can increase it to 20, 25. And within a couple weeks you can get them to go 30minutes without needing it. ”