Teachers at Norman Thomas High School are threatening to stage a one day strike if the Department of Education doesn’t designate their workplace an “impact school” and allow them to separate troublemakers from more studious peers.

The threat of a walkout comes less than a week after a brawl erupted in the Manhattan high school’s cafeteria, leading to the arrests of a dozen students. Teachers from the school say the December 8 incident and other problems throughout the school year are a result of an overcrowded environment purposefully fashioned by the Department of Education.

“What we’re requesting is that Randi Weingarten lead us in a one-day job action,” the leader of the United Federation of Teachers chapter at the school, Nick Licari, said, adding that he has talked to Ms. Weingarten, president of the union, directly requesting her support in the matter.

“There are certain things that we’ve asked for that are not taking place,” Mr. Licari said. “There are certain things the administration is incapable of doing because of funding issues. But they are responsible for creating this situation at Norman Thomas. They are the ones who also need to help us resolve it.”

The faculty met Monday to discuss the situation at the school, which is located between Park and Lexington avenues on 33rd Street. In a nearly unanimous vote, more than 100 teachers approved a motion to stage a one-day strike, though the state’s Taylor Law forbids teachers from striking, threatening hefty fines and jail time.

“Is it worth it? Absolutely.” Mr. Licari, a social-studies teacher, said. “To me, it’s not a strike. It’s a safety issue. It’s not a violation of the Taylor Law. It’s a safety issue. Do you want your children to be safe? Do you want your family members to be safe at work? This is what we’re contending with at many of the schools.”

Six years ago, Mr. Licari said, there were 1,800 students at Norman Thomas. “It was a large school. It was a functioning school. It was a diverse school,” he said. Last year, he said, the building was overcrowded with 2,400 students, and this year it is “extremely crowded” with more than 2,700 students.

Among the teachers’ demands, Mr. Licari said, are:

* Creation of a nighttime program for about 500 students with behavior problems who are “stealing educational time” from their studious peers.

* Designating Norman Thomas an impact school, which would bring more school-safety officers into the building.

* Creating a GED program at the school for high-risk students.

* Establishing a “late room” for students who arrive to school late so they don’t disrupt hallways and classrooms.

Although Mr. Licari, who has been at Norman Thomas since 1979, said there is wide support for a one-day strike, he said he didn’t want to move forward with the job action unless Ms. Weingarten, the union president, is encouraging him and the other teachers.

At this point, Ms. Weingarten isn’t saying no to the idea, but she isn’t giving it her endorsement either.

“The talk of a job action is a manifestation of the staff’s frustration at the overcrowding that has put huge obstacles in the path of hardworking teachers trying to do their jobs,” she said in a statement.

She said she reached out to Mr. Licari after last week’s “riot.”

“The safety issues at the school are serious, and the staff has suggested that Norman Thomas become an impact school, and that evening instruction and other programs be created for disruptive students,” she said. “In the last 24 hours, I shared these perfectly reasonable requests with the Department of Education and we will be aggressively following up.”

The schools chancellor’s press secretary, Jerry Russo, would not predict whether or not the teachers at Norman Thomas would strike, but he said: “We continue working with the UFT and school leadership to address any legitimate concerns.”