A decade ago, an academic research team produced a massive report on the shortcomings in how California’s K-12 schools educate about 6 million children and adolescents.

The “Getting Down to Facts” report was issued just as a very severe recession hammered California and school financing, most of which comes from the state’s income-tax-centered revenue system, took a beating.

Jerry Brown reclaimed the governorship in 2011, and since then many changes in K-12 education have occurred.

WeeklyWalters: your Friday newsletter for all of Dan's columns.

Taxes were raised to dramatically increase per-pupil spending; some of the money was focused on helping poor and English-learner students close the achievement gap between them and more privileged classmates; the state adopted Common Core standards; and its accountability system was drastically revamped to downplay academic testing in favor of “multiple measures.”

Today, a successor team of more than 100 researchers, once again assembled by Stanford University and Policy Analysis for California Education (PACE), released a follow-up study.

It found that while “California’s education system is moving in the right direction…, large achievement gaps persist”; the system needs more money, needs to enhance pre-kindergarten education and needs a better system of using data to chart achievement.

Although “researchers have documented the steady progress California has made on student test performance, they also have found that California continues to lag the nation, with both lower average scores and greater disparities among student groups relative to other states.”

While there’s broad agreement in education circles that closing the achievement gap is critical, there’s been virtual war between the state’s union-led education establishment and a coalition of education-reform and civil-rights groups over how best to do it.

It’s been fought in the Legislature, in local school systems, in the state school board and in the courts.

In fact, the new Stanford/PACE report was previewed last week at an “education equity forum” in Sacramento that delved into the achievement gap’s causes and cures.

The study appears to take somewhat of a middle position in the fierce achievement-gap debate, and its findings provide new ammunition for both sides while also bolstering the support from both sides for raising school spending.

How much?

The researchers conclude that “while public schools in California spent about $69.7 billion on school operations in 2016-17, an additional $22.1 billion—32 percent above actual spending—would have been necessary for all students to have had the opportunity to meet the goals set by the state Board of Education. On a per-pupil basis, the adequate district-level cost was estimated to average about $16,800 per student—the amount of money viewed as needed to allow students in a typical California school to meet the state’s goals if it were spent effectively. In contrast, the comparably defined actual California district-level spending was only $12,750 per student.”

Thus, the report presents a political challenge just as California is about to elect a new governor and a new state superintendent of schools.

A 32 percent increase is just about what both candidates for superintendent, Marshall Tuck and Tony Thurmond, advocate, even though they represent opposing sides of the equity war.

However, the additional $22.1 billion cited in the report would require the biggest tax increase in California history, three to four times as much as the income-tax hike on the richest taxpayers that Brown persuaded voters to pass in 2012 on promises that it would help the schools.

That issue will fall on the next governor, almost certainly Lt. Gov. Gavin Newsom.