Teenagers have kept parts of their lives secret from the prying eyes of adults for generations. A degree of privacy is necessary to develop one's own identity, and to learn to solve problems independently on the path to becoming an adult.

But the hidden aspects of today's teen culture are vastly different from those in the pre-social media era. The secret spaces of this generation are contained behind a screen to which teens are nearly continuously connected.

Most parents know that technology has dramatically changed how teens communicate; they have become much more aware of the legal and social dangers of sexting, and the emotional harm of cyberbullying. But they may not realize the impact of the most significant change this era has enabled: the easy accessibility and near-constant presence of pornography. And they remain largely unaware of how it has changed the way teens interact, the way they view themselves and their sexuality, says author Nancy Jo Sales.

In "American Girls: Social Media and the Secret Lives of Teenagers," Sales details a new frontier of sexism and harassment that has become the reality for girls today. Even though girls aren't the primary consumers of online porn, their social interactions are guided by a hypersexualized porn-saturated culture, she argues. Sales interviewed more than 200 girls in six cities for this book. She presents teen girls' struggles and anxieties in their own words -- words that parents need to hear.

The confluence between the tech, porn and social media industries delivers graphic, violent and degrading images regularly to children's screens, even before they begin to seek it out. Clicking on a benign topic or a "trending" hashtag on Instagram or Twitter will commonly bring up pornographic images -- and the content is vastly different and more violent than what might have been seen in a magazine passed around a playground decades earlier.

Girls who raise their voices against it are dismissed as prudes who "have no chill."

Sales describes scenes in which boys hold up their phones, playing porn, during a girl's class presentation if the teacher is sitting in the back of the room.

Is anyone going to responsibly argue that this is OK? she asks.

There is a stark difference between being "sex positive" and wanting your child exposed to violent and degrading sexual images. Sales cites research that suggests that when boys have their first sexual experience by watching pornographic videos on a screen, it becomes much easier for them to think of women as objects to pleasure them. Sex is reduced to a woman's performance. She cites additional research that shows exposure to porn is related to male sexual aggression toward women.

And many kids' first sexual experiences happen over social media now.

"There is a generation of kids who are self-generating porn, and yet it's become so normalized so quickly that people are trying to dismiss it," says Sales. Young teens she interviewed describe how boys try to blackmail them into sending nude pictures of themselves.

In fact, some of the world's most popular social media sites began as a way to evaluate whether girls and women were "hot or not." That idea was the basis for Facemash, the precursor to Facebook, and the founders of YouTube have said they originally set out to create a hotness-evaluating video site.

A lot of men in Silicon Valley have become filthy rich and powerful off of teenage girls, Sales argues, yet they have taken no responsibility for the ways in which this hypersexualized culture has negatively impacted girls' lives.

She recalled a conversation she had with a friend, a father of a 17-year-old boy, in which she shared her surprise at how much porn teenage boys were consuming (according to studies she'd been reading). The father said he doubted his son watched very much.

The father approached her weeks later, after looking through his son's browser history. He'd discovered that not only was his son watching hard-core porn, he was looking at it right when he woke up in the morning, as soon as he got home from school and again before he went to bed.

The father was alarmed and troubled by both the content and the frequency, she said.

"Kids don't say at the dinner table, 'I saw a great porn video today,'" she said.

The takeaway for parents is twofold: First, parents need to talk with their children about porn, and not just about how to avoid it. There has to be a discussion about the ways it is influencing culture, teen interactions and self-image.

Secondly, we need to demand better protections for kids by the tech industry that profits from children's use of their products. Sales points out that in 2013, Britian's four largest Internet service providers agreed to institute "family-friendly filters" that automatically block pornographic websites unless households chose to unblock them.

Her book raises a fundamentally critical question: Why should porn profiteers and Silicon Valley flourish at the expense of a generation of American girls?

It's time to answer that question.

Jake Hoffner was 10 years old the first time he went to Camp Encourage in Kansas City, Missouri, more than 200 miles away from his home near St. Louis.

His mother, Tracey Gibson, was scared he would hate it. Jake had never even had a play date before. He had never been part of a team. He had never made a friend.

Jake has Asperger's syndrome, a condition on the autism spectrum. Camp Encourage is a three-night, four-day camp for children on the spectrum.

"I wanted him to experience camp," Tracey said. "I wanted to see if he could make friends."

Around this time of year, many parents start planning the summer for their children. The most desired camps and activities fill up fast, so the race begins in the winter or early spring. For the parents of kids with special needs, making summer plans can be even more of a challenge.

But thanks to an increasing number of specialized camps, summer can be a chance for these kids to fit in with a group in a way they can't the rest of the year.

During the school year, children with special needs -- whether social, physical or emotional -- are often "mainstreamed" into classrooms with typically functioning kids. The same thing happens in the summer: Many camps find ways to accommodate children with special needs and integrate them with other campers. But there is a growing demand for camps that cater to very specific populations.

Beyond camps for children with physical disabilities, developmental delays or learning disabilities, there are camps for burn victims, bereavement camps for those who are grieving, and camps for children with serious or chronic illnesses such as cancer or asthma.

For some of these kids, these specialized summer experiences help them grow in ways that neurotypical children may take for granted.

Jake, now 15, will be attending Camp Encourage for the sixth summer this year. He wrote a letter about how much those days mean to him.

"Camp Encourage is a very important part in my life. This is because every time I come, I know I'll meet old friends. And come back with new ones."

When his mother read this line aloud, she started crying.

"I'm sorry," she said. "I don't usually hear him talk this way."

Kelly Lee, executive director at Camp Encourage, says the camp, which costs $1,200 for a four-day session, offers scholarships to several of the students who attend. For families who may also be paying for therapies during the school year, additional expenses can put these opportunities out of reach.

"Every year we have a waiting list," Lee said. "Our focus is on meeting needs -- knowing how important tiny details can be to this population, and tailoring to those needs."

The benefits that attract parents to these kinds of camps include a specially trained staff, which has experience dealing with the population they will be serving; the opportunity to get additional services, enrichment or therapy in a camp setting; and the chance for the child to be surrounded by peers who share some of the same challenges.

Some of the kids deal with stares or questions during the school year, like burn victims who have to explain the scars that cover their bodies. Others don't get invited to birthday parties, or face bullying at school.

Jake captured that in his letter, when he wrote that the camp "lets in the kids that either have trouble making friends or the kids who don't realize how cool they are." Meanwhile, "the kids who may have bullied them, tormented them or just ignored them are left out."

His mother said the drive to Kansas City each summer is worth it for those few days.

"He lights up," she said.

John Garvilla recognized his daughter's natural athletic talent when she was 5 years old.

Garvilla, who lives in the St. Louis area, is a former college soccer coach and athletic director, so he spotted her abilities early. She was fast, coordinated and loved playing ball.

Samantha Garvilla, now 18, started playing soccer and basketball competitively when she was 8 or 9. She excelled at both, and her father could see her playing as a high-level athlete in the future.

She was 11 when she tore her right ACL. Her father told her she had to choose between basketball and soccer; there was no way she could play both, having suffered this injury. He even tried to push her toward golf.

"I have an artificial knee," he said. "I didn't want my daughter to walk like me."

Samantha chose soccer, and played year-round. She trained hard and stood out on the field.

She was 12 when she tore her ACL again.

After the rehab, she was undeterred. She refused to quit the sport she loved.

During her freshman year of high school, she was recruited by Darlington School in Rome, Georgia, to attend the boarding school on a soccer scholarship. She was training four to six hours a day at school, and she loved it.

"It was the best thing that ever happened to me," she said.

The team was getting ready for regionals the beginning of her sophomore year. She was playing in a scrimmage when she went in hard for a tackle.

"Right away, I knew what it was," she said. "By the third one, you know."

It was the ACL in her left knee this time. The surgeon told her that there was no way she could go back onto the field.

"Your knees are not going to hold up," he told her. "You're not going to last." It wasn't just the three torn ACLs: She has also suffered 12 meniscus tears and undergone 10 surgeries.

She came back to St. Louis to finish her sophomore year. She was devastated to leave Darlington, but still refused to leave the game entirely.

The beginning of her junior year, she decided she wanted to play goalie, a position less prone to the injuries she's had. In a young athlete's career, this was a late time to switch positions, but she told her parents she was committed to playing.

"There are certain things you can't teach," her father said. "Speed, height, athleticism. She has a teachable spirit. She loves the game."

He made sure she had access to the best trainers in the country. She didn't have the experience playing goalkeeper in as many games as her peers, but she was fearless. Her family started getting contacts from Division 2 colleges. They sent her highlight reel to more places, and then the offers from Division 1 schools started coming in.

"What a lot of people saw was raw talent," John said.

They took their daughter to visit some of the colleges around the country that were recruiting her. They were still considering the offers when Samantha asked her father to take her to the doctor.

She had bruised her back in practice, and her entire abdomen was hurting. The doctor asked if she had been feeling bloated, and she said she had.

She wasn't injured, the doctor explained after she ran a test.

Samantha was pregnant.

She called her mother, Kim, hysterical. Kim picked her up, and they walked out the back door while the doctor broke the news to John.

When she saw her father, she broke down and said, "Daddy, people are going to point at me and say, 'That's the girl who ruined her life.'"

John told her that people may point, but that God had a plan for her.

"You're going to get through this," he said. "We're going to count this baby as a blessing."

Kim said she went through all the stages of grief about the loss of what her daughter's future could have been. She suggested considering adoption, but Samantha said she wanted to keep the baby.

Her parents are still raising a 15-year-old and two 13-year-old sons, so they told her this child would be her responsibility, although they would support her and help her as much as they could.

Samantha cried a lot. She told her boyfriend, who was shocked but supportive. She couldn't accept the idea of giving up her baby.

"I had the ability to raise him. I have the support of my family. There was no reason (to give him up), except it would have been easier for me," she said.

She delivered her son, Braxton, on Feb. 11.

Shortly after the delivery, Samantha told her mother that it was good that the baby came a few days early: This way, she'd have six weeks off and be back in time for practices by spring break. She would be ready to play when the season starts in her senior year.

After graduating, she will play soccer on a scholarship at St. Charles Community College. She plans to use her financial aid to pay for daycare.

"The dream has never wavered," Kim said.