who that is. >> let's look a little more closely at that. this instagram user says he's 18. following a 13-year-old girl. >> there is actually a lot of people i have no idea who they are, but i just let them follow me because the more, the merrier. >> gabby, like many middle schoolers in this study, shares a lot of her life on social media, sometimes even more than she realizes. take a look at this instagram post. she wants to show her friends she's tanning at a lake. seems innocent enough, but any follower who clicks on this photo can pinpoint exactly where she is. that's because of the locator function that she didn't even know was turned on. according to the fbi, there are more than half a million sexual predators online every single day in america and they regularly create fake online profiles to groom unsuspecting verdicts. >> for a certain group of young people, they want to attract as many as possible.