Don Fisher, co-founder of the The Gap chain, passed away on Sunday. Not only was Fisher a partner in the construction of a vast retail empire that would make any entrepreneur proud, he was also a partner in funding the expansion of the KIPP chain of charter schools — something that would make any philanthropist proud.

Thanks to the $60 million that he and his wife Doris committed to KIPP’s growth, it now serves 20,000 students in 82 schools across America. In k‑12 education, public or private, that level of growth is unusual.

But how can it be sustained? How can those who share Mr. Fisher’s commitment to bringing excellent educational options within reach of all children ensure that his efforts are not simply maintained but expanded? And how can we ensure that not just KIPP but any similarly excellent school can scale up to serve a mass audience? These are questions that the education policy community desperately needs to answer.