When researchers at Weill Cornell Medical College scanned teenage brains, they found that the area that regulates emotional responses has to work harder to keep impulses in check. Courtesty Kristina Caudle/Developmental Neuroscience hide caption

itoggle caption Courtesty Kristina Caudle/Developmental Neuroscience

Beer pong and other drinking games are popular among teenagers, and play a role in binge drinking. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Teenagers put in more than two hours a day of TV time on average, still more than what pediatricians say is healthy. iStockphoto.com hide caption

itoggle caption iStockphoto.com

I told him he would break his arm if he did that. But he did it anyway. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Teenagers turn to their phones and social media to find rides. Tanggineka Hall/Youth Radio hide caption

itoggle caption Tanggineka Hall/Youth Radio

The X-ray reveals a blowdart lodged in a teenager's windpipe. Reproduced with permission from Pediatrics @AAP hide caption

itoggle caption Reproduced with permission from Pediatrics @AAP

Soda bottles and household chemicals are sometimes used to make low-power bombs. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Dylan Young, then 18, posed for a photo as a vehicle cruised by North Arlington, N.J., in June 2012. Young was in a fender-bender accident caused by being distracted while texting and driving. Julio Cortez/AP hide caption

itoggle caption Julio Cortez/AP

Brad McDonald and his 14-year-old daughter, Madalyn, are working to understand each other during her teenage years. Courtesy of Brad McDonald hide caption

itoggle caption Courtesy of Brad McDonald