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

Pakistanis walk on an island that emerged off the coastline of the Arabian Sea following a deadly magnitude 7.7 earthquake in Pakistan's southern province of Baluchistan on Sept. 24. Gwadar local government office/AP hide caption

itoggle caption Gwadar local government office/AP

Party On: Legislation passed last week allows the Federal Helium Reserve to continue selling the stockpiled gas. Above, Jonathan Trappe launches his 370-balloon craft from Caribou, Maine, in an attempt to cross the Atlantic Ocean on Sept. 12. Alexandre Ayre/Barcroft Media/Landov hide caption

itoggle caption Alexandre Ayre/Barcroft Media/Landov

SpaceX launched an upgraded version of its Falcon 9 rocket Sept. 30 from Vandenberg Air Force Base in California, northwest of Los Angeles. SpaceX hide caption

itoggle caption SpaceX
iStockphoto.com

Workers assemble solar panels at the now-bankrupt Suntech in the eastern Chinese city of Wuxi. Overproduction in the country has helped lower the cost of solar panels. Peter Parks /AFP/Getty Images hide caption

itoggle caption Peter Parks /AFP/Getty Images

A wildfire burns in Prescott, Ariz., on June 18. The fire covered nearly 11 square miles of the Prescott National Forest. Todd Tamcsin/AP/American Red Cross hide caption

itoggle caption Todd Tamcsin/AP/American Red Cross

Shinichi Kuramoto of the Center for Deep Earth Exploration in Japan displays a replica of earthquake fault rock. TOSHIFUMI KITAMURA/AFP/Getty Images hide caption

itoggle caption TOSHIFUMI KITAMURA/AFP/Getty Images