May 18, 2009 3:32 pm 7th Grade Math? There's an App for That Two enterprising Chicago 7th graders have developed their own application that turns your iPhone into a math tutor — and they’re dividing the profits by two. US & World Videos 2:32 How water pollution is changing how Imperial Beach lifeguards protect people 2:56 Pro-Palestinian protesters move to downtown jail 3:03 San Diego photographer remembers Callum Robinson, surfer found in Baja 2:41 Friends and family remember 3 surfers who disappeared in Mexico 2:47 Jewish community gathers for Holocaust commemoration in La Jolla