In his 2009 annual letter, Bill Gates lamented that many of the high schools his foundation funded did not improve student outcomes in a meaningful way. Although many of the schools did have higher attendance and graduation rates, they had not graduated more college-ready students. However, Gates wrote that a few successful non-selective schools serving mostly poor students had been effective in raising expectations and student achievement. These schools were successful in helping teachers be more effective and "almost all of these schools are charter schools that have significantly longer school days than other schools."
Based on these findings, the Gates foundation has "refined its strategy." In the name of innovation, he's has been advocating for mayoral control of schools and greater funding for, and fewer limits on charter schools.
Of course, some charter schools are great and some of them are not. I wonder if there are lessons Gates may have missed. After spending $2 billion, was nothing else learned about these successful schools other than the fact that they're charters and have longer days?