After spending several billion dollars attempting to reform public education over nearly 20 years, the Bill & Melinda Gates Foundation is saying that, oops, the job is harder than its leaders had thought.

Sue Desmond-Hellmann, foundation chief executive officer, wrote this in a newly released annual letter:

We are firm believers that education is a bridge to opportunity in America. My colleague, Allan Golston, spoke passionately about this at a gathering of education experts last year. However, we're facing the fact that it is a real struggle to make system-wide change.

And she wrote this about the foundation's investment in creating, implementing and promoting the Common Core State Standards:

Unfortunately, our foundation underestimated the level of resources and support required for our public education systems to be well-equipped to implement the standards. We missed an early opportunity to sufficiently engage educators – particularly teachers – but also parents and communities so that the benefits of the standards could take flight from the beginning.

This has been a challenging lesson for us to absorb, but we take it to heart. The mission of improving education in America is both vast and complicated, and the Gates Foundation doesn't have all the answers.

That may be news only to the Gates Foundation. As this new biting editorial in the Los Angeles Times — with the headline, "Gates Foundation failures show philanthropists shouldn't be setting America's public school agenda" — says:

It was a remarkable admission for a foundation that had often acted as though it did have all the answers. Today, the Gates Foundation is clearly rethinking its bust-the-walls-down strategy on education — as it should. And so should the politicians and policymakers, from the federal level to the local, who have given the educational wishes of Bill and Melinda Gates and other well-meaning philanthropists and foundations too much sway in recent years over how schools are run.