When Christian Herr saw in a news alert earlier this month that Acero charter teachers in Chicago had gone on strike, he felt a mixture of admiration and pride.

“I was just really excited, especially for a lot of the things they were specifically asking for,” Herr said.

Herr is a science teacher at Chavez Prep Middle School, the first charter to unionize in Washington, D.C. The demands of Acero teachers felt in line with what he hoped his union would bring — protections for undocumented students, a shorter school year, and better pay.

The nation’s first-ever strike of charter teachers, when some 500 unionized teachers at Acero charter schools in Chicago walked off the job earlier this month, reverberated across the country. It grabbed the attention of charter teachers like Herr and their employers, as well as of the broader education community that may have regarded charters as on the fringes of their interests — until now.

Herr, whose union, like Acero’s, is associated with the American Federation of Teachers, said, “I am proud that we are both part of the same national group.”

National labor experts, union officials, and charter teachers say the impact of the strike won’t hit the industry immediately — but when it comes, it could be big.

“I think it’s historic,” said Richard Kahlenberg, director of K–12 equity and senior fellow at the Century Foundation, a progressive think tank aimed at reducing inequality. “I think this strike could be pivotal in expanding a movement that right now is small but has the potential to grow a great deal.”

The charter strike could link two disparate, and sometimes hostile, groups: teachers at publicly run schools and those in charter schools. The strike also could portend changes for the charter sector itself and the future of unions more broadly.

Experts estimate that 10 percent of charter schools are unionized. The American Federation of Teachers represents 7,500 charter school employees at 236 schools in 15 states. Chicago has the highest proportion of charters with union contracts, at 25 percent, but Los Angeles has more union teachers at charters.

Acero teachers succeeded in negotiating wage increases, smaller class sizes, and a shorter school day, in part because as private employees they could legally bargain over more topics.

That win, said Steven Ashby, a labor professor at the University of Illinois at Urbana-Champaign, could go a long way to convince other charter teachers that unionizing could help solve problems in their classroom.

“More charter teachers may strongly consider organizing after seeing what a short strike can get them,” Ashby said. “For those that are already unionized, I think they may be less likely to take tiny, incremental change, and instead look at the example of Chicago and say: Look, we can really win.”

Katharine Strunk, a professor of education policy at Michigan State University, agreed.

“It seems like a very good signal for other charter schools that if they were to unionize, they would be able to get the outcomes they want,” Strunk said. “It’s a bellwether moment where this could spawn consecutive striking situations by other unionized charters.”

But efforts to unionize charter teachers still face challenges. In June, the U.S. Supreme Court ruled in Janus v. AFSCME that labor unions could no longer collect fees from employees on whose behalf they negotiate, but who haven’t joined the union as full members.

Janus dealt a blow to public-sector unions. But unionizing charter school teachers could be a way for unions, like the Chicago Teachers Union, to continue to build a membership base.

Henig says that means they need to continue to attract members who think they have something to win. “A more militant union in some ways may be a more exciting one to attract members,” he said.

But what about the traditional approach of bodies, like the Chicago Teacher Union, as charter skeptics?

Strunk said unions that have been anti-charter would have to walk a fine line to walk when unionizing charter schools.

But, she said, it’s also possible that with more teacher input spelled out in stronger contracts, charter schools may become better for students.

“Unions’ reasoning has been that charters are not good for kids for many reasons,” Strunk said. “If now they can bring charters into the fold and create union contracts that resemble the traditional contracts they’ve negotiated, they might feel differently about the benefits these schools will have for kids.”

The strike also highlighted the similarities in contract demands of charter teachers and educators at district-run schools — about class size, budget cuts and workloads.

“Even though they are operating in two different systems that in some ways have been designed to bang heads with one another, the key issues that teachers face are often pretty similar,” said Jeffrey Henig, a professor of political education at Columbia University.

Kahlenberg sees the precedent-setting strike harkening back to the original ideas around charter schools sketched out by Albert Shanker, considered one of the original visionaries of charters, as laboratories where new ideas in education could be tested and teachers would have more input.

“Shanker very much wanted charter schools to be a place where teachers had a greater voice in how schools are run,” he said. “I think we are coming full circle back to Al Shanker’s vision, in this case through the use of a strike.”

In Chicago, the effects of the strike could be felt sooner rather than later. The Chicago Teachers Union is actively negotiating 10 contracts at charter networks, two for the first time.

And teachers at the Noble Network who unsuccessfully have tried to unionize for several years and whose founder recently resigned after allegations of improper conduct with alumni, watched the Acero strike closely.

“Educators at Noble have been talking about it with their colleagues,” said Casey Sweeney, lead organizer with Chicago ACTS, which has unionized charter schools and is under the umbrella of the Chicago and the state- and national-level teachers unions.

“It would have been hard to imagine a charter strike when the Acero union was first certified” about five years ago, Sweeney said. “But it has made me incredibly hopeful for what is possible, for educators at Noble, to win.”