A head-scratching puzzle of school reform over the past century is the innovation that arrives in tinsel and enters tax-supported public schools. Often districts adopt such glittering new programs and they settle into protected niches. But, and here is the puzzle, praised and admired as they are, they cannot break out of that nook. They stick around at the edges of the system remaining isolated, failing to spread throughout the district.

Early 20th century Progressives had their Project Method and the Dalton Plan. Both were adopted in many public schools because they seemingly solved organizational, curricular, and instructional problems. And they had internal constituencies of teachers and administrators yet they remained on the periphery of school systems. They did not become standard practices across classrooms.

Mid-century curricular reformers had their New Math. Late-20th century insurgents rallied around Coalition of Essential Schools and Core Knowledge programs. And early 21st…