Do Charter Schools Replicate?

Wall Street Journal, via a kind reader:

One critique of charter schools is that while a few energetic principals show success, it’s impossible to replicate. Not so, says a new study of Boston’s charters, which doubled from 16 schools to 32 in four years, even as they maintained their effectiveness.

This is great news, especially given the magnitude of the extra learning: A year of attending one of these charter spinoffs, the study suggests, improves math scores by an amount equivalent to about 40% of the “achievement gap” between Massachusetts’ black and white students.

The paper’s authors, three professors of economics or education policy, explain what happened after Massachusetts raised its charter cap in 2010. The state set rules encouraging successful charter schools—deemed “proven providers”—to seed new campuses. Most follow a “no excuses” framework, with high expectations and a low tolerance for misbehavior.

After the cap was lifted, growth came rapidly. By 2015 the share of Boston’s sixth-graders attending a charter school had risen from 15% to 31%. Yet applications increased even faster, to the point that there were two hopefuls for each open seat. Oversubscribed charters award admission by lottery, which randomizes the results. “Comparing the outcomes of students who receive lottery offers to those that do not,” the authors write, shows “large positive impacts of charter attendance on test scores.”