Did Bill Gates waste a billion dollars because he failed to understand the formula for the standard deviation of the mean?  Howard Wainer makes the case in the entertaining Picturing the Uncertain World (first chapter with the Gates story free here). The Gates Foundation certainly spent a lot of money, along with many others, pushing for smaller schools and a lot of the push came because people jumped to the wrong conclusion when they discovered that the smallest schools were consistently among the best performing schools.

Personally, I think the education debate has fundamentally shifted from the question of SHOULD we use data (to measure student growth, school quality, educator effectiveness, and other topics) to HOW do we use data. If you are of the former opinion, this is certainly not for you.  But anyone interested in the latter should take a look, as this is an instructive example of a well-intentioned mistake.

And human fallibility being what it is, the ability and willingness to learn from our mistakes — math and all — is a pretty good shorthand for what most folks consider progress.