The Common Core got caught up in an old-fashioned culture war, one that pitted activists on both the right and left, who came to detest the Core, against an education policy establishment that was sometimes surprised by the fierce resistance to its actions.

“There is so much space between the people who cook up these policies and the classroom,” said Amy Wilkins, a longtime advocate in Washington for racial equity in education, and currently senior vice president at the National Alliance for Public Charter Schools.

“We underestimated how difficult it is to change a big, entrenched system,” she said of the broad education efforts of the past two decades.

A Rocky Start

The Common Core began, in part, as a response to the bipartisan No Child Left Behind Act of 2002, the sweeping federal mandate that required all schools to test students annually in reading and math, in the third through eighth grades and once in high school.

The law was largely seen as a disappointment. It allowed all 50 states to set their own standards and create their own tests, making it impossible to compare students across the country, let alone American children to children abroad.

In response, in 2009, the National Governors Association and the Council of Chief State School Officers, a coalition of state superintendents, formed a working group of consultants, educators and experts tasked with drafting shared national standards in English and math.

In 2010, Kentucky became the first state to adopt the Common Core. The vast majority of states and territories followed. But soon after, the initiative ran into both logistical and political roadblocks.