Allyah* is a good kid. Like most teens, she cops an attitude occasionally, but she obeys her parents and teachers and sets a good example for her three younger siblings. When she was in the ninth grade, however, Allyah’s grades suddenly nosedived.

“We couldn’t figure out what was going on,” says Allyah’s mom, Erin Campbell of Orlando. “We thought anxiety, bullying or some secret thing was troubling her.”

The “secret” Erin’s self-described tech-geek husband uncovered? Twitter. Allyah had been sending thousands of tweets at all hours from an account her parents didn’t even know she had. The Campbells quickly shut her down: #Busted.

Like it or not, children are influenced by social media, and the number of new social media outlets available to them is growing, from Facebook, Twitter and Instagram to, Snapchat and Vine. While most parents estimate their kids’ social media time at two hours a day, the youngsters themselves say they spend five hours daily on tweets and posts, according to the Family Online Safety Institute.

If your child has a phone or Internet access, it’s likely that he already has a social media presence—which means he could be at risk. So it’s imperative that you teach him about online safety the same way you would prepare him for the real world. Here’s how:

GET REAL. You may be tempted to “just say no” to social media, but taking a hard line won’t dent its influence. Pew Research Center’s Internet & American Life Project says 81 percent of 12- to 17-year-olds use social networks. It’s how they communicate with their friends. Your best bet is to try to manage your kid’s use, not ban activity altogether.

GO AHEAD. PRY. Find out what sites your little one frequents, who her “friends” are and what they are posting. The only way to do those things is to follow her. But don’t sneak around; ask for access, tell her up front that you’ll be reading her posts—and make that a requirement for social media privileges. Explain that you’re just doing it to keep her safe. Promise not to judge or jump in unless there’s a serious concern.

TALK ONLINE DANGER. Your child knows better than to talk to a stranger on the street, but may not be sophisticated enough to understand the risks of “oversharing” online. Teens will innocently divulge details like their school, activities or current location. But that, along with the pictures they post, makes them easy-to-find targets. Pew researchers discovered that one in six teens reports being contacted by a stranger in a way that made him or her feel uncomfortable or scared. Explain that any personal information that can identify your children needs to stay private, including requests that come via pop-up contests, surveys and so-called giveaways.

BE PHONE SMART. If your youngster has a smartphone, you may want to set up data usage and time blocks through your wireless provider to keep her from visiting these sites during class time and bedtime. T-Mobile offers Web Guard and Family Allowances, for example. Use My Verizon to set up FamilyBase alerts, which apprise you of her mobile activity.

TEACH THEM E-ETIQUETTE. Kids often hide behind their keypads, saying things they’d never say face-to-face. Speak with them about what is and isn’t appropriate. Help them understand that foul language, gossip, sexting and bullying are no more acceptable online than they are in real life. In fact, inappropriate posts can be even more damning because they can live on in cyberspace forever.

*Subjects’ names have been changed.