Khan Academy’s polyglot and free online courses seem tailor-made for a pandemic-struck globe. Not surprisingly, the platform has seen massive increases in signups and use. The education nonprofit, founded in 2008 by HBS graduate Sal Khan, now serves over 100 million students in 190 countries. As schools contemplate reopening, it is developing tools for getting students ready for the next grade and providing a mix of in-class and online instruction. To handle the surge in demand, the donor-funded operation will need a corresponding boost in investment in search of social return.