“Competition between public and privately managed schools in Philadelphia over the past two years has allowed all public school students to benefit from best practices and has led to overall achievement gains for Philadelphia students that are dramatically above the state average.
…
The gains achieved in Philadelphia are among the highest of any of the nation’s largest school districts, according to the Council of Great City Schools. Moreover, the gains in student achievement occurred in contracted “partner” schools as well as traditional public schools, providing the first substantial evidence that the city’s public-private school management experiment, aimed at turning around the district’s lowest-performing schools, is working.” Emphasis added

So writes Lisa Snell at RPPI.