We're all familiar with the term "hidden in plain sight." Well, there may be no better way to describe the nation's 6,900 charter schools.
These publicly-funded, privately-run schools have been around since the first one opened in St. Paul, Minn., in 1992. Today, they enroll about 3.1 million students in 43 states, so you'd think Americans should know quite a bit about them by now. But you'd be wrong.