Charter schools have become the next big thing in education, with President Obama's education secretary, Arne Duncan, a supporter and philanthropists like Bill Gates promoting them. But while there are high-profile examples of charter schools lifting poor minority students to academic success, the national numbers fare much worse. A comprehensive study last year by Stanford University found that only one-fifth of charter schools in America outperformed public schools on standardized tests, with about half offering equivalent numbers, and over a third, 37 percent, performing "significantly worse." Replicating the results of top-performing schools like the thriving Harlem Success Academy in New York has proved difficult, The New York Times reports, with superficial similarities (such as school uniforms) at other institutions sometimes masking major deficiencies in teaching methods.