On Thursday night, parents, students and members of the Jefferson County, Colorado community railed against the conservative majority school board, which sought to review and revise the AP U.S. History course curriculum in the district. (Jeff Simon/The Washington Post)

In comfortable suburbs such as this one on the outskirts of Denver, school board meetings are normally sleepy events.

But at last week’s session of the Jefferson County Board of Education, hundreds of people lined up two hours in advance to get in. One man waved a copy of George Orwell’s “1984” at the board. Two high school students hauled in cardboard boxes containing 40,000 signatures to a petition they had circulated online. Another one told the five-member panel, “America was founded on what you are trying to prevent!”

Jefferson County has become ground zero for a new culture fight — this time over how to teach U.S. history to high-achieving 10th-graders.

At issue are changes to the Advanced Placement history course, one of the academically rigorous classes high school students across the country take in hopes of earning college credit and impressing admissions officers at selective schools. Last year, nearly 440,000 students took the AP history exam, one of the most popular AP tests offered.

The College Board, which administers exams to students upon the completion of AP courses, has revised the history curriculum in ways that have angered conservatives, who say it paints a darker picture of the country’s heritage and undervalues concepts such as “American exceptionalism.”

The debate is one in a series of fights across the country over political influences in the classroom, the role of teachers unions and market-based approaches to improving education, such as performance-based pay for teachers and school choice.

Here in Jefferson County, controversy over the new AP standards boiled over in recent weeks after the school board’s recently elected conservative majority pushed back at the College Board. The school board plans to set up a new committee to review the curriculum with the goal of assuring that courses — in the words of board member Julie Williams — “present positive aspects of the United States and its heritage” and “promote citizenship, patriotism, essentials and benefits of the free enterprise system.”

Williams also wrote that “materials should not encourage or condone civil disorder [or] social strife” — which is exactly what has happened across Jefferson County as a result of the plan. There have been teacher “sickouts” that shut down two schools, walkouts by thousands of students and a massive community protest Friday along the county’s main boulevard.

The parent-teacher association also opposes the review committee. “It’s not just AP history — it’s an open door to censorship,” said Michele Patterson, president of the 13,000-member PTA.

On Sept. 19, the Texas State Board of Education went on record against allowing the new AP curriculum framework in state classrooms. Legislators and activists in South Carolina and Tennessee are discussing similar moves. And at its summer meeting in August, the Republican National Committee passed a resolution branding the curriculum “a radically revisionist view of American history that emphasizes negative aspects of our nation’s history while omitting or minimizing positive aspects.”

The new framework also came up at last month’s Value Voters Summit in Washington, a conservative meeting that drew a number of possible 2016 GOP presidential contenders. Ben Carson, a pediatric neurosurgeon who is considering a White House bid, told the gathering that the new AP history framework is so anti-American that “I think most people, when they finish that course, they’d be ready to sign up for ISIS,” the Middle Eastern terrorist group also known as the Islamic State.

Turmoil in Colorado’s second-largest school system could have implications for the 2014 elections, with closely fought battles underway in the state for a U.S. Senate seat and the governorship. Jefferson County is considered a political bellwether of how Colorado as a whole will vote.

Among those at Thursday night’s school board meeting here was Kyle Ferris, who had organized a walkout by his fellow students at Columbine High School, known nationally as the scene of a mass shooting in 1999.

Ferris acknowledged that there was more than a little irony to the fact that students in his school and others were “skipping to say we value our education. There’s an irony, but it’s an appropriate irony.”

But some came to show their support for the proposal. Kara Johnson of Arvada, who has three children in Jefferson County schools and who majored in history in college, said she was concerned that the new curriculum was “reviewed by college professors, and college professors are, by and large, on the left. . . . American exceptionalism is something our kids need to believe in, and that exceptionalism is absent from this new framework.”

The new AP history curriculum adds two periods: life in the Americas from 1491 to 1607, which addresses the conflicts between Native Americans and European settlers, and from 1980 to the present, which includes the rise of social conservatism and the battles over issues such as abortion, as well as the fight against terrorism after the attacks of Sept. 11, 2001, and demographic and economic shifts of the 21st century.

College Board officials say the revision was made to encourage analytical thinking and stress that it is a framework, meaning that teachers choose their own curricular materials and can add topics deemed important by their communities.

James Grossman, chief executive of the American Historical Association, which has endorsed the new AP course, said the choice is between “a more comfortable national history and a more unsettling one.”

“There’s always pressure to use history to unite a people, to create a comfortable sense of yourselves,” said Grossman, who sent a letter admonishing the Jefferson County school board and applauding the student protesters. “We do it in our families. You have a set of family stories that makes your children feel comfortable and proud, and you have stories about some of the not-so-great things. Is it better to tell children just the comfortable things, or should they learn the rest? ”

Adding to the furor among conservatives is the man who leads the College Board, David Coleman. He was a key architect of the Common Core State Standards, which are reviled by conservatives, tea party groups and some liberals. Coleman joined the College Board in 2012 after the revisions had been made to the AP U.S. history course, according to a spokeswoman for the company. Still, he has become an incendiary figure among conservatives.

National groups, from the American Principles Project on the right to the American Civil Liberties Union, on the left have jumped into the fray in Jefferson County.

In an unprecedented move, the College Board has threatened to withdraw recognition of the county’s AP U.S. history courses if the school board changes the way the course is taught. That could hurt students’ college prospects. More than 3,300 colleges and universities around the world use AP scores for credit, placement or admission decisions.

Tensions in Jefferson County have been brewing since last November, when a conservative majority won seats on the five-member school board with an eye toward making policy changes.

Labor relations quickly soured as the new majority moved to institute a merit pay system for teachers, over the objections of a third-party “fact-finder” who ruled that the district’s teacher evaluation system was not reliable enough to use as a basis for salary decisions.

“We approved a compensation model for the first time, assured that all our effective teachers receive raises,” the board president, Ken Witt, said. “We set aside the union-backed plan of steps and levels that had no recognition for performance. The day after that meeting, two of our schools had to close because of strikes via sickouts.”

Many of the protesting students were rankled by questions that have been raised about the motivations behind their walkouts. “What’s up with these punks?” Fox News host Gretchen Carlson asked. Witt suggested they have been “pawns” of the teachers unions.

“You appear to have no respect for us, and you say these things to protect your political base,” Eric Temple, a senior at Evergreen High School, told the board. But he added, “Thank you for your lesson in civil disobedience.”

Layton reported from Washington. Alice Crites contributed to this report.