Teachers at Mundo Verde Bilingual Charter school in Washington have made efforts to form a union, the second unionization attempt by charter school teachers in the District over the past two years.

The teachers at the Truxton Circle school say they’re concerned about health care benefits and a lack of transparency around decisionmaking. In August, Mundo Verde’s executive director sent an email to staff saying there would be an increase in health care costs, a larger portion of which would have to be shared by employees. That email, according to two of the teachers behind the organizing effort, took the staff by surprise.

“So a group of us got together to think about how we could advocate and, you know, [speak] our truth,” said Andrea Molina, a teacher at Mundo Verde.

Afterward, the staff drafted a letter expressing their discontent with the school’s leadership and asked for more say in decisionmaking.

“And since then, we have been organizing understanding that, you know, we’re not doing this just for us educators but also for our students and our families,” Molina said. “That is our commitment to making sure that students receive what they need, and timely still, but also that the rights of educators are respected every day.”

Now, according to the American Federation of Teachers, more than 80 percent of teachers and staff at the school have signed union authorization cards. They’ve asked the school to recognize the union voluntarily.

Mundo Verde would be the second D.C. charter school to make an effort to form a union. In 2017, César Chávez Public Charter School, a middle school in Northwest D.C., became the first charter school to form a union in the District. That school is now slated for closure.

Molina and Danielle McCormick, a fourth-grade teacher at Mundo Verde, said the teachers at César Chávez have been supportive of their efforts.

On Thursday, the teachers will meet with Mundo Verde’s leadership. If the school doesn’t recognize their union, they’ll petition the National Labor Relations Board.

Mundo Verde’s executive director, Kristin Scotchmer, said in a statement that the school wants a transparent and inclusive process moving forward.

“We know that every member of the school team seeks to make Mundo Verde the best it can be,” Scotchmer wrote. “As a result, we need to include all members of our community in this conversation, including those that have reservations about unionization. There is good reason to consider deliberately any implications for Mundo Verde and our school community if a labor contract were to govern how teachers and other staff interacted with administrators, students, and families.”

This story originally appeared on WAMU.