It’s back-to-school time. Soon, girls and boys will be saying goodbye to summer and heading back to the classroom. But we know that doesn’t mean they’ll get to books and learning. Many of today’s kids are heading to the classroom with their Blackberry or iPhone in hand, Facebook account active, and hyper-sexualized clothing on, even at a pre-pubescent age. Suffice it to say, they face some distractions.

Which is why parents, especially parents of teen and pre-teen daughters, should read Girls on the Edge, the latest book by doctor and psychologist Leonard Sax. Sax, also author of Boys Adrift (2009) and Why Gender Matters (2006), sees a lot of distractions keeping girls from healthy development today, and he lists what he finds to be the “four factors driving the new crisis for girls”: issues affecting sexual identity; the “cyberbubble,” including social-networking technologies like texting, sexting, and Facebook; teen obsessions ranging from hyper-competitiveness in school to anorexia and other self-harms; and environmental toxins that bring on premature puberty.

Take his first one, sexual identity, for instance. There’s no doubt girls are dressing sexier earlier these days. Sax recounts the story of one mom whose daughter had chosen as a Halloween costume a French maid outfit complete with “fishnet pantyhose and a frilly miniskirt.” She recalls, “This was an outfit marketed to ten-year-old girls. They even had it in smaller sizes!” “What’s weird,” she continues, is that “boys’ costumes haven’t changed that much from what boys wore when I was little. . . . Boys would dress up as Darth Vader or a Jedi knight or Teenage Mutant Ninja Turtle. And they still do. But so many of the girls today, nine- and ten- and eleven-year-old girls seem to feel as thought they have to dress up in something really skanky. How come? I’ve never heard of a boy who wanted to dress up like a Chippendale’s dancer.”

She’s onto something: This sexualization seems to be affecting girls more than boys, and sexualization is different from healthy sexuality. As Sax sees it, girls who dress sexy “prior to the onset of puberty are not expressing their sexuality. . . . Dressing sexually in the absence of sexual desire is simply conformism.” As psychology professor Stephen Hinshaw of Berkekley sees it, “If girls pretend to be sexual before they are sexual, they’re going to find it much, much harder to connect to their own sexual feelings.”

What is it, then? Self-objectification, really. Girls who dress sexy before puberty, are putting themselves on display like objects, not for themselves but for others. As Sax sees it, “our culture pushes girls to define themselves in terms of how they look instead of helping them to develop a sense of who they are,” and this sets them up for depression, anxiety, and unsatisfying relationships in the future.

Think of a girl you know between the ages of 13 and 16 on Facebook today. Look at her profile picture: Is she smiling? Chances are, no. Chances are, we see someone who is making an expression that is saucy, or rolling-the-eyes irritated, or simply deer-in-the-headlights stoic, but chances are it’s not a smile. Something’s gotten between the girl and her smile, and, as Sax diagnoses it, it’s self-objectification: “As these girls get hyper-connected with their peers, they get disconnected with themselves.”

So it’s not too surprising, is it, that sexting is so prevalent. Sexting, the increasingly popular trend of texting sexually explicit messages or photos via cell phones between peers, is at self-objectifying at the core. In 2008, the National Campaign to Prevent Teen and Unplanned Pregnancy surveyed teens and young adults about sexting and posting explicit materials online and found that 39 percent of teens are sending or posting sexually suggestive messages, and 48 percent reported receiving such messages. Girls in great number are volunteering nude photos of themselves to boys, and it’s becoming a legal mess in many states, where it’s tough to distinguish this from child pornography.

And you can imagine how, with hyper-connected technologies, playground bullying has reached a new level. One Ohio girl, Jesse Logan, sent a nude photo of herself to a boyfriend who later sent the image on to other girls in her class; she was harassed to the point of skipping school and ultimately killed herself in 2008. While this is an extreme case, it touches on a real problem of how much more brutal cyberbullying can be for girls:

Cyberbullying can be completely anonymous. Twenty years ago, if a girl wanted to spread rumors about another girl, everybody would know who was doing it. That knowledge constrained what the bully might say. If you got too nasty, your nastiness could reflect badly on you. But now you can pretend to be a boy who’s just received sexual services from Leeanne, then post something about Leeanne online, and nobody will ever know you are actually a girl who invented the whole story to make Leeanne look bad.

All this, for Sax, perpetuates the great problem girls face today—a diminished sense of self, which leads a greater likelihood of experiencing depression, anxiety, and inclination to turn to drugs, alcohol, or other self-harming obsessions.

As Melinda Tankard Reist, in her recently published book Getting Real: Challenging the Sexualization of Girls, reports:

Eight-year-old girls are admitted to hospital with eating disorders. Schoolgirls develop ranking systems on the basis of “hotness,” resulting in guaranteed misery for the girl with the lowest ranking. Cyberspace has become a central area for bullying where girls are universally judged. Many feel they are dying a social death and disintegrate emotionally. For some, emotional disintegration leads to physical disintegration with the ultimate tragic outcome.

Of course we can’t turn back time and erase the sexualization kids face everywhere or rewind to the pre-Facebook days. But, with books like these, parents can increase their awareness of what kids are facing today and be more involved. Even parents with a laissez-faire attitude about teen sex and technology want their kids to do their best in school. And with matters of life and death increasingly on the line, one thing’s for sure: Math class is on the backburner.

But we have to ask ourselves: How did we get here? And where do we go from here?

Mary Rose Somarriba is the managing editor of First Things.