Keep computers in a common area so you can monitor what your kids are doing. It's a longstanding directive for online safety -- but one that's quickly becoming moot as more young people have mobile devices, often with Internet access.

A new report from the Pew Internet & American Life Project finds that 78 percent of young people, ages 12 to 17, now have cell phones. Nearly half of those are smartphones, a share that's increasing steadily -- and that's having a big effect on how, and where, many young people are accessing the Web.

The survey, released Wednesday, finds that one in four young people say they are "cell-mostly" Internet users, a percentage that increases to about half when the phone is a smartphone.

[...]

Despite the ability to monitor some phone activity, some tech and communication experts question whether surveillance, alone, is the best response to the trend.

Some parents take a hard line on limits. Others, not so much, says Mary Madden, a senior researcher at Pew who co-authored the report.

"It seems like there are two extremes. The parents who are really locking down and monitoring everything -- or the ones who are throwing up their hands and saying, `I'm so overwhelmed,'" Madden says.

She says past research also has found that many parents hesitate to confiscate phones as punishment because they want their kids to stay in contact with them.

"Adults are still trying to work out the appropriate rules for themselves, let alone their children," Madden says. "It's a difficult time to be a parent."

Read More