(Jung Yeon-JE/AFP/Getty Images)

Teens are spending more than one-third of their days using media such as online video or music — nearly nine hours on average, according to a new study from the family technology education non-profit group, Common Sense Media. For tweens, those between the ages of 8 and 12, the average is nearly six hours per day.

The Common Sense census was designed to set a new statistical baseline for research on teen and pre-teen media use, said Jim Steyer, the group's executive director. Even as someone who spends all day looking at these issues, Common Sense Media executive director Jim Steyer said he was staggered by the amount of time that young people are spending consuming media — and how little the government has done to explore what that means.

"Where is the research?" Steyer said. "We're conducting the biggest experiment on our kids — the digital transition — without research."

It's hard to fully judge how much screen time has increased in recent years. The closest study to Common Sense Media's may be the Kaiser Family Foundation's 2010 study, which estimated an average of five-and-a-half hours of media use for those ages 8-10, 8 hours and 40 minutes for those aged 11-14, and just under 8 hours for 15-18 year-olds.

The Common Sense study, which surveyed 2,600 youths, used a different methodology than the Kaiser Family Foundation, so it is difficult to make a direct comparison between the two findings.

But there is a definite upward trend, said Steyer, and media use is getting more and more ubiquitous.  Teens are often multitasking with media on in the background. "Everything is digital," he said. "We are now in the true emergence of digital natives; that has enormous implications for anyone who cares about media, technology and children."

For many parents, the amount of time kids are spending watching video, listening to music, texting and posting may not be a surprise. Even those who have taken steps to limit their children's media use find that it's hard to compete the allure of a glowing touchscreen.

"It's funny how addictive it can really be," said Bruce Williams, a New York City father of two. His children, he said, are probably more limited in their screen time than others. Williams and his wife didn't even give their daughter a flip phone until the 6th grade, well past the time many of her peers had smartphones. Their 10-year-old son has never had a piece of tech gadgetry to call his own, though he may soon if — like his sister — he attends a middle school that requires him to take the subway.

No member of the family, Williams said, uses Facebook.

But his 13-year-old daughter, who got her first smartphone this year, does have active Instagram and Snapchat accounts, he said. And while she's far from an addict herself, he said, it does seem as if she's often itching for screen time. "She's a good kid and a good student," he said, with a chuckle. "But every moment when it's not homework time or playing-an-instrument time, you'll see her grab a phone, sneak away, and do whatever it is they do."

So what are these kids today doing in all those hours of screen time? In some ways, they're doing things teens have always done. Among tweens, the most common media activities are watching TV and listening to music. Among teens, the activities are the same, though music edges out the television. For tweens, playing mobile and video games, plus watching online videos, round up the top five activities. Teens watch videos, play video games and use social media.

There were also some interesting socioecomic differences in the study. Tweens and teens from lower-income families spend more time using media, on average, than higher-income teens. The study says that it’s not necessarily that lower-income kids are more likely to use media, but rather that those who do are heavier media users. For example, the study says, while fewer low-income teens watch TV or videos on a given day, those who do watch for 90 more minutes than their higher-income counterparts.

Black youth report spending far more time with all types of media than Hispanics or whites, averaging 11 hours and 10 minutes of media use per day. That’s over two hours more than the average amount for whites or Hispanics. While all teens are equally likely to use social media on a given day, black teens reported that they spend far more time doing so.

When it comes to keeping an eye on what their kids are doing, parents have different approaches. Williams and his wife have full access to their daughter's smartphone, and keep the lines of communication open to make sure she's only friends with those her own age. Most parents, according to the study, do the same. Fifty-three percent of teens and 72 percent of tweens say their parents have talked with them about how much time they spend using media — even more say they’ve had conversations about content.

Just because they're talking about it, however, doesn't mean that parents understand what's happening all of the time. A quarter of teens who go online say their parents know very little about what they do; 30 percent say the same about social media use.

"As a parent, it's incredibly hard to stay up to date on what the latest thing is," said Terri Markwart, the president of the Langley High School parent-teacher association in McLean. Markwart said she has clear rules about tech and social media use with her three children — one in middle school and two in high school. Her kids also got their phones relatively late; in the sixth or seventh grade. In their house, no phones are allowed at the dinner table.

The same is true of the kids' rooms when they go to bed. When Markwart remodeled her kitchen, she installed a cabinet charging station where the whole family keeps their phones at night.

Markwart said that when she thinks about how screen time affects her kids, she worries most about the effect on their ability to hold a conversation. "You could have a room full of teens together in a classroom or a hallway, hanging out for a little bit, and they're all on their phones," she said. "They’re together, but they’re not together." So while she certainly isn't draconian about her children's technology use, she does try to preserve the precious time when they're all together.

She's also had frank conversations with her kids about the costs of social media use. Her kids have Facebook accounts, she said, but they've also talked about the costs of posting every aspect of their lives. Feelings can get hurt, for example, when you find out all of your friends are hanging out without you by way of some photo tags. And she's also made sure they're aware what their digital actions can do to their reputations — something particularly important as they fill out college applications.

"I have to give Langley credit," she said. "The counselors there told the kids to go radio silent on social media in their junior year."

Parents talked about the benefits of tech use as well. Elizabeth Hale, president of the PTSA at Longfellow Middle School, said that while she limit her sons’ tech use, she also loves that she can communicate more easily with them during the day. (At 13 and 14, she noted, they probably won’t take kindly to lunchbox notes saying “Good luck on the test!” anymore.)

When it comes to setting limits around screen time, Hale said she mostly tries to model the right behavior for her kids. Her boys don’t yet drive, for instance, but she makes a point of not using her phone behind the wheel — one way she tries to lead by example.

“This is something we didn’t have growing up,” she said. “It’s a new area for us."

For all the debate about what the appropriate place of technology should be in most kids' lives, the study also highlighted how many people are still cut off from that conversation altogether.  Steyer noted that the study found there's a serious digital inequality gap — one that only becomes more concerning as more of students' school work goes online.

One in ten teens from lower-income homes have only dial-up internet, as compared with none from higher-income teens surveyed. And while just over half of lower-income teens have smartphones, that’s far lower than the 78 percent reported by higher-income teens.

Steyer said that the technology industry should do more to help close that gap. Company efforts have been "very small scale at this point," he said. "I think the tech industry has a huge role to play here," he said, noting that the tech industry's clout has helped it lobby successfully on issues such as net neutrality and the Stop Online Piracy Act.

"They should be leading on this issue," he said. "They haven't been. That doesn't mean they can't."