The American school reform movement has been aggressively focused on teacher quality for four decades. Just ask Hillary Clinton. She made an early name for herself by promoting a basic skills test for Arkansas teachers in 1983.

Along with higher academic standards, school choice and more learning time, better training and more careful selection of teachers have been key reform demands. The policy magazine Governing said in 2013 that “teacher quality affects student learning more than any other school-based variable.”

But in a surprising and insightful new book, one of the reform movement’s founding fathers, E.D. Hirsch Jr., has denounced that fixation on fixing teachers. This is a major blow to making individual teacher quality a factor in salary and promotions, as governors, foundations, President Obama and other reform leaders have advocated.

Hirsch, the smartest 88-year-old I know, is now professor emeritus of education and humanities at the University of Virginia. His book, “Why Knowledge Matters: Rescuing Our Children From Failed Educational Theories,” leaves no doubt how off-track he thinks the movement he helped start has gone.

He says we have been callously blaming teachers for meager results of reform when the real culprit is what they have been asked to teach. Most school lessons, he says, are an uncoordinated mishmash of concepts with little importance placed on the vocabulary and key facts that produce good readers. Without a curriculum that allows teachers to build on each other’s work and help students learn words at the core of modern civilization, more teacher training will not get us very far.

“The underlying theory of the reforms . . . has been that schools are teaching skills that can be developed by any suitable content,” he writes. “That mistaken theory has allowed the problem of grade-by-grade content to be evaded.”

That quote above from Governing magazine, he writes, is wrong. Citing research by Brookings Institution scholar Grover “Russ” Whitehurst, Hirsch says “a better curriculum can range from being slightly to dramatically more effective than a better teacher. That’s not surprising when you consider that the curriculum is what teachers teach and what students are supposed to learn.”

Hirsch is not only a founder of the reform movement but the inspiration for its most important, and controversial, new product, the Common Core State Standards. The dream that the standards would lead to a vibrant curriculum rescuing American schools from mediocrity has, Hirsch says, fallen victim to a lack of specificity and a lazy acceptance of whatever the textbook and testing companies thought they could sell to states and school districts.

The Common Core language arts standards, for instance, emphasize “finding the main idea, managing complex texts and reading closely,” Hirsch says. Yet improvement in these abilities does not depend on practicing these skills, but on “how much students know and how big their vocabularies are.” In the Core Knowledge curriculum Hirsch helped invent, the third-grade unit on ancient Rome is full of challenging vocabulary, geography and politics and fits nicely with the lessons on ancient Greece those students had in the second grade. That is not what you see in most classrooms today.

Improving curriculum is harder than improving standards. Textbook publishers know that teachers don’t like big changes, so they don’t provide them. But some ambitious educators are moving toward more specific lesson plans. The nation’s largest charter school network, KIPP, has for the first time produced an English and math curriculum for all of its schools that want it.

Hirsch still supports improved teacher training. He doesn’t mind states that drop the Common Core standards, as long as they institute what he calls “specificity, coherence and cumulativeness of knowledge across the grades.”

That’s a mouthful. But without it, our teachers will probably struggle for improvement and many of our children will remain poor readers.