Harry Jackson left the Fairfax County School Board meeting Thursday night feeling frustrated. The father of a Thomas Jefferson High School sophomore, he had signed up to address the board about sexually explicit material in the school library, including work he and other parents say normalizes pedophilia. But the list of speakers ended right before his two minutes at the mic.

A student who did speak that evening defended the contested material, saying “there is nothing that is inappropriate unless you go looking for it.” Mr....

Fairfax county parent Harry Jackson, who serves as president of Thomas Jefferson High School’s Parent Teacher Student Association.

Photo: Asra Nomani

Harry Jackson left the Fairfax County School Board meeting Thursday night feeling frustrated. The father of a Thomas Jefferson High School sophomore, he had signed up to address the board about sexually explicit material in the school library, including work he and other parents say normalizes pedophilia. But the list of speakers ended right before his two minutes at the mic.

A student who did speak that evening defended the contested material, saying “there is nothing that is inappropriate unless you go looking for it.” Mr. Jackson takes it as a backhanded admission. “I am glad to see we agree there’s pornographic material in the library,” he says.

Thomas Jefferson isn’t just any public school—U.S. News & World Report ranks it No. 1 in the nation—and Mr. Jackson isn’t just any parent. Earlier this year, he was elected president of the school’s Parent Teacher Student Association, or PTSA. A graduate of the U.S. Naval Academy and a retired naval intelligence officer, he’s one of thousands of American parents taking on their school boards across the country.

Like many of those rallying outside Thursday night’s meeting, Mr. Jackson wore a T-shirt saying “Parents are not ‘domestic terrorists.’ ” It’s a reference to a Sept. 29 National School Boards Association letter asking President Biden to investigate threats or disruptions at school board meetings as a possible form of “domestic terrorism.” In response, Attorney General Merrick Garland ordered the Federal Bureau of Investigation and U.S. attorneys to look into the threats.

All this has transformed once-dull school board meetings into increasingly raucous encounters between parents and officials. On so many of the hot-button issues of the day—from mask mandates and lockdowns to critical race theory, transgender policy and racial preferences for admissions—the public schools have become the vanguard for today’s progressive agenda. But parents such as Mr. Jackson aren’t taking it any more, and they show no sign of relenting.

“Did the NSBA really think through what it was saying?” Mr. Jackson asks. “Because you don’t negotiate with terrorists. You hit them with a drone strike, or ship them off to Guantanamo.”

Already we’re starting to see clarifications trickle in. Last week, the Virginia School Boards Association distanced itself from its parent organization, saying it was “not consulted” on the NSBA’s letter and that this is “not the first disagreement that VSBA has had with its national association.”

As for Mr. Jackson, until two years ago he considered himself an ordinary dad, refereeing lacrosse and basketball games and serving as a board member for an organization promoting gifted-and-talented programs. What provoked him to take on a more activist role was the school board’s decision last year to replace Thomas Jefferson’s highly competitive entrance exam with a new formula designed to increase the number of black, Latino and white students at the expense of Asian-American students. “In the name of equity they established inequity, and it was clearly directed at the Asian community,” Mr. Jackson says.

So in August 2020 Mr. Jackson and other like-minded parents formed the Coalition for TJ, and earlier this year he ran for the PTSA. He and three other reform candidates won their races and the Virginia PTA responded with a letter threatening to revoke the Thomas Jefferson association’s charter. The state group cited “continual disregard and a series of violations of organizational standards,” but Mr. Jackson and other Coalition for TJ members see it as another effort to silence their voices.

Mr. Jackson and other protesting parents are often assumed to be angry white working-class Trump supporters. But this is Fairfax County, where Mr. Biden trounced Donald Trump by 42 points. Mr. Jackson is African-American, and of the coalition members elected with him, two are Chinese-American and one is Indian-American.

“Our coalition destroys their narrative,” he says. “Most of our members are Democrats, and many are people of color.”

Mr. Jackson sees the school board protests as fallout from the Covid-19 lockdowns. “Because kids were home and learning online, parents got a look at what their kids were being taught in the classroom, and they didn’t like it,” he says. “Now they’re speaking up.”

They’re also learning the school system isn’t interested in what they have to say. Terry McAuliffe, Virginia’s Democratic candidate for governor, confirmed suspicions during a recent debate when he declared, “I don’t think parents should be telling schools what they should teach.” It was the ultimate gaffe—a politician inadvertently telling the truth.

Mr. Jackson would say it’s all been an education. Apart from the specific disagreements he has with the school board, the experience is teaching parents like him something far more disturbing. Which is that the most important public institution in their children’s lives no longer regards itself as accountable to the public.

Write to mcgurn@wsj.com.

Journal Editorial Report: The social media giant's role in making girls miserable. Images: AFP/Getty Images Composite: Mark Kelly The Wall Street Journal Interactive Edition