BRASILIA, Brazil (AP) — When students at Ceilandia state school No. 7 in Brazil's capital came back from their break in February, they were met by two dozen uniformed police officers in a place they barely recognized anymore.

Guns in their holsters, the officers ordered students to form rows in the schoolyard. The students were given white T-shirts pending the arrival of their new uniforms. From now on, hair would have to be kept short for boys and tied at the back for girls. No more shorts, caps, brightly colored nail varnish, earrings or any distinctive pieces of clothing. Students arriving late wouldn't be let in.

"Sometimes we feel intimidated," said Michael Pereira da Silva, 17, who was against the decision to hire police to instill military-like discipline in the school. "Just going out into the hall, we are obligated to bow our heads or say hello to police officers."

Although experiments began in previous years, the quasi-military approach is one of the most visible educational efforts being championed under new President Jair Bolsonaro, a far-right former army captain who campaigned on promises to improve Brazilian schools, which are widely recognized as a problem. A 2015 study by the Organization for Economic Cooperation and Development ranked educational performance in Brazil as 63rd out of 72 countries and regions.

Schools now being co-run by police are modeled on Brazil's exclusive military colleges, which tend to perform better than most public schools — a fact that makes many parents eager to see similarly rigid discipline.

Under the model, teaching remains in the hands of the Education Ministry, while police officers oversee discipline and enforce a new code of conduct. Implementation of the pilot program in a school must be approved by a majority of parents, teachers and school staff in a referendum.

The Ceilandia school is one of four in Brasilia that voted to take part. Officials in Brazil's capital hope to add 36 more schools by the end of the year and reach a total of 200 by 2022. Bolsonaro's administration is pushing similar expansions nationwide, though it has yet to say how many it plans to convert across the country.

Some states have been exploring the model since the early 2000s, but a large expansion worries many education experts and teachers' unions, who say such schools can become exclusionary and go against the concept of a free, open-to-all public schooling system.

They argue that these schools have managed to improve results because problematic students are quietly replaced by better-performing ones, often from wealthier backgrounds. Another red flag for critics is the introduction of guns in schools, particularly in the nation that leads the world in total homicides each year, the majority from firearms.

"Increased gun access and possession are not associated with protection from violence," said Robert Muggah, research director at the Brazilian think tank Igarape.

The expansion is a flagship measure of the Bolsonaro administration although the Education Ministry says it has no data on how many such schools existed or studies on long-term benefits of the model.

Besides putting police in more schools, Bolsonaro's administration has been pushing for other changes in public education, accusing it of being filled with "Marxist ideology." The Education Ministry has talked of revising history textbooks to refer to Brazil's 1964-1985 dictatorship as a "democratic regime of force" and of excising references to feminism, homosexuality and violence against women. Most recently, Bolsonaro said public funding for sociology and philosophy could be eliminated.

In recent years, some schools taken over by the police have garnered headlines when prosecutors have had to intervene after officers began charging monthly fees to parents, imposed expensive uniforms or sought to set aside half of the school's places for children of police officers.

In 2016, the head of education for police in the state of Goias revised the school system's internal regulation that normalized "expulsions" and "forced transfers" of students. The move followed a recommendation from state prosecutors who argued that expulsions from public schools must remain a last recourse.

"It's not for everyone, that's for sure," said Mauro Oliveira, deputy-secretary at the Brasilia state education ministry. Only a small number of students have been turned away from their schools since police arrived, he said, arguing the ends justify the means.

The administration says it is targeting violent and low-performing schools or those in at-risk areas, where drug trafficking takes place or paramilitary groups operate.

"We're not talking about normal schools," Oliveira said. He cited cases of students and teachers not being able to go to school because they were bullied or threatened. "Is this not exclusion as well?"

According to the head officer in Ceilandia state school No. 7, Edney Freire, the duties of police officers, called "monitors," include making sure students don't fight.

"If for instance there is any kind of friction between students, the monitor is going to go talk with the students, call the parents to solve the problem," he said.

It doesn't always work out in such calm fashion. A video posted this month on the internet news portal G1 shows police officers intervening in a fight in the school's gymnasium. Footage shows an officer body-slamming a student to the ground.

In Ceilandia, a crowded working-class neighborhood on the outskirts of Brazil's capital, violence against teachers was not so much the problem. But drug traffickers operated unfettered around the school and vagabonds were regularly seen drinking and using drugs in the area.

When the news came out that the school would enter in a partnership with the police, many parents sought to sign up their kids. Some arrived two days before the school opened, camping outside to make sure to get a spot for their child when the doors opened.

Students must line up in the school yard daily, heels together, arms straight along their bodies, heads looking straight forward toward the school's Brazilian flag.

"We must prepare our future starting today," Freire, the head officer, told students lining up on a recent day.

During his speech, police officers walked down the rows, checking students' posture and writing down the names of those breaking any rule.

The school's director, Adriana De Barros, said that in just two months discipline has improved. Petty crime has also gone down, Freire said.

Adriana da Silva, the parent of 17-year-old student Vitor, said it was "amazing" that it was April and she had not been called in by the school to discuss the teen's conduct even once.

"He used to get in trouble. Now he wants to become a military man," da Silva said.

___

Associated Press writer Diane Jeantet reported this story from Rio de Janeiro and AP photojournalist Eraldo Peres reported in Brasilia.