Charter schools are the fastest-growing sector of public education, taking root in most U.S. states, thanks to a big push by the education reform lobby [1] and the federal government’s Race to the Top competition. And since the movement’s inception in the early 1990s, its founders have learned a few things, the Huffington Post reports. Across charter schools, there are similarities in what works to boost student achievement. A 2011 study [2] identified five successes of charter schools: “frequent teacher feedback, the use of data to guide instruction, high-dosage tutoring, increased instructional time and high expectations.” But just because charter schools have the flexibility to become successful in these ways doesn’t mean all of them meet those five criteria. In fact, most probably don’t…