Daniel Denvir writes that it is time for candidate Bernie Sanders to wade into the education issues. Denvir hopes that Sanders will attack the segregation that is at the root of so many urban problems today. " Americans have a lot in common when it comes to getting fleeced by the billionaire ruling class, which only a populist multi-racial movement can overthrow. But inequality also has a geography, and that grim map is chiseled into America’s separate and unequal neighborhoods and schools. Sanders would do well to make note of that in Philly, where he is speaking -- a city whose public schools have been ravaged by failed reforms for more than a decade under state control. Denvir interviews a variety of experts about why neither Sanders nor Clinton has taken on education. 50 million children are enrolled in America's public schools, and yet those schools are under attack