At school these days, the cell phone is now as common as the backpack.
Teens say they don't know anyone who doesn't have a cell phone.
Cell Phones Welcome in School
And four out of five teens admit to sleeping with their cell phones or keeping them near their beds.
At Fairfax High School in Los Angeles, phones are banned in the classroom. But lunchtime is a cellular feeding frenzy, with most students banging out text after text after text.
Most of it's just "'How have you been?' 'What are you doing today?' 'How was your weekend? -Normal stuff," said texting twin sisters Chantell and Chanell Daniels.
Read more from the Pew Internet & American Life Project
The average adult sends just 10 text messages per day, but older teenage girls - aged 14-17 - send about 3,000 per month.
Sixteen-year-old Annie Levitz sent about 4,000 per month. She now has carpal tunnel syndrome and needs surgery.
"I started, like, losing feeling in my hands and they'd go numb and I'd be going to pick up dishes and things and they would just fall out of my hands," she said.
Social studies teacher Mike Stryer says some of his students admit they're hooked.
"I mean, they actually say we are 'addicted' to texting and it's interfering with their studies and their lives," Stryer said.
Texting is now the main way teens communicate with their friends. So some parents are concerned that their kid's no longer sit down and simply have a conversation.
"The problem here is we don't get the nonverbal training that we need for later in life, on a job interview, talking with a friend, consoling friends," said child psychologist David Swanson. "We're missing that along the way."
But to teens glued to their phones, that's one message that apparently isn't getting through.