In the Gates Foundation’s annual letter, dreamily entitled “What If…,” CEO Sue Desmond-Hellman writes of past progress and future goals. The foundation aims to save the world from what Bill and Melinda Gates consider its greatest problems: namely, infectious diseases, cigarette smoking and the American education system. This year’s letter reveals that of the big three, it’s the education overhaul—throwing money at Common Core to bring it live coast-to-coast—that’s presented the most unforeseen challenges.

This acknowledgement of the bumpy execution echoes a criticism of the broad-scale curricular reset many teachers have voiced since its implementation across more than 40 states started in 2010. That is, that rebuilding every lesson or designing years of original curricula to meet stifling new test-driven standards requires more time and attention than any classroom teacher has to spare, and more guidance and preparation than have been provided. That’s not to mention controversial requirements that math and science teachers instruct students in unfamiliar methods—at an ultimate disservice to their test scores: In the spring of 2015, public high school seniors, who had been exposed to Common Core math since fourth grade, showed a decline in their scores over the last two years.