David Hermlin is a singer, dancer, musician and songwriter — oh, and a global activist, too. Sample lyric: "I will fight for my dream, and I will never give up." Courtesy of David Hermlin hide caption

itoggle caption Courtesy of David Hermlin

They're members of the global-minded teens club: (left to right) Toluwanimi Sola-Adeyemi of Lagos, Chloe McGill of Seattle and Emine Arcasoy of Chapel Hill. Courtesy of Tolu Sola-Adeyemi, Chloe McGill and Emine Arcasoy. hide caption

itoggle caption Courtesy of Tolu Sola-Adeyemi, Chloe McGill and Emine Arcasoy.

Research into how the human brain develops helps explain why teens have trouble controlling impulses. Leigh Wells/Ikon Images/Corbis hide caption

itoggle caption Leigh Wells/Ikon Images/Corbis

Jackie Fortin's daughter, Cassandra, last summer. Courtesy of Jackie Fortin hide caption

itoggle caption Courtesy of Jackie Fortin
Maria Fabrizio for NPR

An inmate at Rikers Island juvenile detention facility carries a plastic fork behind his back as he walks with other inmates. A recent report found that juvenile detainees are subjected to routine violence, both by other inmates and by correction officers. Julie Jacobson/AP hide caption

itoggle caption Julie Jacobson/AP

Jamira, 11, is an aboriginal girl in Australia. "I like being special," she says. "I like being — you know — different than everyone else." Henrik Nordstrom/I Am Eleven hide caption

itoggle caption Henrik Nordstrom/I Am Eleven

About 40 percent of high schools start before 8 a.m., which contributes to chronic sleep deprivation among teens, according to the American Academy of Pediatrics. Chris Waits/Flickr hide caption

itoggle caption Chris Waits/Flickr

Dr. Donald Brown inoculated Kelly Kent with the HPV vaccine in his Chicago office in the summer of 2006 — not long after the first version of the vaccine reached the market. Charles Rex Arbogast/AP hide caption

itoggle caption Charles Rex Arbogast/AP