At least taxpayers didn’t foot the bill. (Update: Apparently, taxpayers did foot some of the bill.)

Anyway, Education Week lays it down.

The Bill & Melinda Gates Foundation’s multi-million-dollar, multi-year effort aimed at making teachers more effective largely fell short of its goal to increase student achievement—including among low-income and minority students, a new study found.

This conclusion to an expensive chapter of teacher-evaluation reform shows the difficulty of making sweeping, lasting changes to teacher performance. The results also demonstrate the challenges of getting schools and teachers to embrace big changes, especially when state and local policies are in flux.

The Gates Foundation was in full spin mode.

“We believe that this work, which originated in ideas that came from the field, led to critical conversations and drove change and partnerships across the country,” said Allan Golston, the president of the U.S. program at the Gates Foundation, in a statement. “We have taken these lessons to heart, and they are reflected in the work that we’re doing moving forward.”

Perhaps the Gates Foundation folks should take a trip to New York City and observe what charter schools like Success Academy have done to raise student achievement for disadvantaged students.