Before Common Core came along, California parents, faculty, and officials spent years developing some of the best-ranked K-12 math requirements in the nation. One result of their careful work was more than tripling the number of eighth graders who ranked proficient in math, and quadrupling the number of eighth graders taking algebra.

By 2014, California was the top state in the nation in eighth-grade algebra enrollment. That was the year Common Core went into place. It erased all those gains almost immediately, shows a new Hoover Institution analysis.

The shocking graphs in the study by Bill Evers and Ze’ev Wurman tell the whole story in one glance. Here’s one. For reference, the Obama administration pushed states into Common Core in 2010, but it started phasing into schools at the earliest in 2013, and more in earnest in 2014 and 2015. That’s right when all the achievement jumps off a cliff.

“[I]n the four years under Common Core, the number of eighth graders taking Algebra I in California dropped precipitously to 19 percent in 2017, taking California back to where it was around 1999, when early algebra taking was the privilege of the elite. And while all demographic groups lost ground, the loss for Latino and African American students was much deeper than for white and Asian Americans,” write Wurman and Evers, who both vainly voted against California adopting Common Core on a state commission. The graph below shows the deeper damage to minority students in more detail.

While the highest-achieving nations make eighth-grade algebra the default, in the United States it has been more typical for students to take algebra in ninth grade. Common Core also pins the bulk of an algebra course to ninth grade, but its supporters still promised the nation their force-fed sandwich of curriculum mandates and federally required tests would boost student achievement to match that of international peers. Yet they did this not by actually raising the bar for what students would learn in states like California, but redefining success and taking away the public’s ability to measure it.

Here’s how. To improve their ability to compete for federal education grants during the Great Recession, states had to get their university systems to agree to not remediate students who passed Common Core exams. This is how Common Core deceptively achieved its public promise of getting all students “college and career-ready.” State higher education systems simply agreed to allow Common Core to define what constitutes college-ready. Take out definition, insert Common Core. Presto.

One problem with that: Common Core does not require enough math for students to actually be ready for college-level classes, especially for those who intend to major in math-related fields. In order for all students to actually be able to meet Common Core’s standards, those standards had to be set at a level that most everyone can achieve without major genuine curricular improvement. In other words, low.

“Common Core defines college readiness below what have traditionally been the prerequisites for essentially all state colleges across the nation—the completion of Geometry and Algebra II courses. Instead, Common Core puts the readiness level at about half of the traditional Geometry and Algebra II content, suitable at best for community colleges,” Evers and Wurman write.

“Since remedial classes are gone this Fall, unprepared students will be placed in specially-designed credit courses—often called corequisite or stretch classes…” In other words, students who cannot do college-level work will nonetheless be told they are doing college-level work and given college credit for explicitly non-college-level work. Kafka, call your office.

In an extremely convenient move that just happens to cover up this deception, at least for a while, like nearly all states California abruptly ended its pre-Common Core tests, plus its end of course exams for classes like algebra and geometry. That means there is no measuring stick by which to equally compare pre-Common Core and post-Common Core tests. They simply stopped the non-Common Core tests one year and started up the Common Core tests the next, with no continuity between the two by which to gauge how Common Core compares to California’s previous high standards.

This is how to explain the graph below, which magically shows that the number of so-called “college-ready” high school graduates doubled overnight. It didn’t. California just dropped the bar and kept the label.

“California has lost much of its ability to monitor students’ progress in high school because of the loss of End-of-Course tests,” say Evers and Wurman. “Since 2014, we have been flying blind” — in California and across the nation. As a rough substitute for having this data, Evers and Wurman examine math achievement in advanced classes, which has also gone south.

Common Core critics warned of all this beforehand and directly after during a wave of parent and teacher opposition once the public was allowed to learn what was going on: the lack of data by which to robustly evaluate how Common Core affects kids, the degradation of math instruction in a country already known for poor math instruction, the especially damaging effects on the most vulnerable kids, the lying to parents, students, and taxpayers about the quality of the classes their kids are taking and we’re all paying for.

We were ignored and belittled, not just by Democrats but by Republicans, in statehouse after statehouse after statehouse. They called us crazy tinfoil hatters and preferred to believe the slick PowerPoints of overcredentialed and underproven “experts” selling snake oil for personal gain. Vindication like this is not what any of us wanted. What we wanted, and still want, is for American kids to stop being used as props for cynical, exploitative politics that destroy their futures. Is anyone going to listen when the next Common Core-style juggernaut rolls around? I’m afraid I really don’t think so.