Yahoo CEO Marissa Mayer delivers the keynote address at the annual Consumer Electronics Show in Las Vegas earlier this month. Robert Galbraith/Reuters/Landov hide caption

itoggle caption Robert Galbraith/Reuters/Landov

Students Blake Jamar (from left), Ryan Clifton and Gregory Gonzales take apart a bicycle that generates electricity at Analy High School in Sebastopol, Calif. Jon Kalish for NPR hide caption

itoggle caption Jon Kalish for NPR