Kids as young as 13 purchase e-cigarettes, or "vape pens," online, where independent sellers don't necessarily ask a buyer's age. Jenny Lei Bolario/Youth Radio hide caption

itoggle caption Jenny Lei Bolario/Youth Radio

Football practice at Castro Valley High School in California. Proper hitting technique requires players to keep their heads up to prevent neck injuries and concussions. Brett Myers/Youth Radio hide caption

itoggle caption Brett Myers/Youth Radio

A growing number of children are entering puberty at younger ages — sometimes as young as 6 or 7. But in many schools, sex education classes don't begin before the fifth grade. Cuneyt Hizal/iStockphoto.com hide caption

itoggle caption Cuneyt Hizal/iStockphoto.com

Zach Brown's preferred mode of transportation is his skateboard. Brown, 27, is an artist and actor who doesn't own a car. Courtesy of Zach Brown hide caption

itoggle caption Courtesy of Zach Brown

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

itoggle caption Tanggineka Hall/Youth Radio

Donta Jackson's snack of choice is a bag of Skittles. Brett Myers/Youth Radio hide caption

itoggle caption Brett Myers/Youth Radio