There are a lot of schools in the U.S. that need to be achieving much better outcomes. However, there is a much smaller group of schools in which achievement levels are appalling. The solutions for garden-variety low-achieving schools are arguably different from those for schools with the very worst levels of performance.
The way we can find out what works is to compare schools or classrooms assigned to use any given program with those that continue current practices. Ideally, schools and classrooms are assigned at random to experimental or control groups. That's how we find out what works in medicine, agriculture, technology, and other areas.
Moving to a focus on evidence-based reform will not solve all of the contentious issues about accountability, but it could help us focus the reform conversation on how to move forward the top 95% of teachers and schools -- the ones who teach 95% of our kids -- and how to put accountability in proper proportion.