These days, kids are bombarded with distractions from TV, smartphones, video games, and of course, social networking sites. It should come as no surprise that checking status updates, chatting with friends, tagging photos and playing games takes time away from studies. But now researchers have proof that all that tech time can interfere with kids’ success in school.

Scientists from California State University, Dominguez Hills found that checking Facebook just once in a 15-minute period resulted in worse performance in school. The report observed middle school, high school and college students’ behavior on Facebook.

To test kids’ studying prowess, researchers asked them to focus on a topic of their choice for just 15 minutes. They found that the more time went by, the more windows students opened on their desktops. The number of windows maxed at around eight to 10 minutes, when on-task behavior also began to drop. When would-be scholars juggled windows and other computer tasks, they performed worse. And those who checked in online even just once fared worse on an exam.

Not surprisingly, when students stayed on task, they did better. So what did we learn from this lesson?

Our brains work better by focusing on one task at a time for up to fifteen minutes. Then it’s OK to take a one-minute break and indulge in a quick gander at Facebook or shoot friends a quick text. Teachers found that without a little tech time, students were distracted anyway.

All that social networking can serve a benefit, though, as other recent studies have found. Kids who surf social media sites typically get an ‘A’ for social aptitude, as they can be more outgoing, show more empathy and develop a stronger sense of identity.

Just don’t let your teen find out, especially if his or her grades are less than stellar.