For years, Teach for America has pointed to YES Prep charter schools in Houston as the epitome of charter success. In her most recent book, Wendy Kopp identified YES Prep as an example of the miracles wrought by charters.

But Gary Rubinstein noticed a strange anomaly in the performance of YES Prep. It doesn’t seem to know how to educate black students. All but two of its schools in Houston serve mostly Hispanic students. The two that enroll a high proportion of black students are F-rated by the state.

Its five high schools have received many plaudits. But they enroll tiny proportions of black students.

It’s founder Chris Barbic bailed out of the Tennessee Achievement zschool District when he saw he was on a track to failure.

What gives?