For students at the Educational Centre 308 in the rundown Brasília neighbourhood of Recanto das Emas, the day begins with a pep talk from Lt Mario Vitor Barbosa Magalhães.
"This week has been very demanding - the vast majority of you have succeeded in doing what's needed of you, both in the classroom and with homework," he shouts. "Very good, but every day we need to improve, every day is a new challenge."
The children then belt out the national anthem, standing in front of the Brazilian flag with its motto "Order and Progress". The aim is to reinforce a sense of national pride that many feel has been lost in Brazil in recent years.
In a way it feels more like a police academy than a school. Here, police are in charge of the discipline, leaving the education to the teachers.
It has been a turnaround, says deputy head Debora Rodrigues Sales, who has been teaching in this school for 20 years.
Until a few months ago, you would more likely see drug traffickers than uniformed officers at the school gate. A sign of it is the bullet mark on the metal door, the result of a recent shoot-out.
"As time went on, people were asking for a police intervention," she says. "When this idea of a school shared with military police came up, we said 'yes' straight away."
Militarisation of schools
There are around 120 "militarised" schools in the country. But the election last year of far-right President Jair Bolsonaro, a former army officer who has promised to crack down on violence and improve education, has propelled their growth more than ever.
Educational Centre 308 is part of a pilot project where management is shared between teachers and police in Brasília. The plan is for the number of these schools to grow from four to 40 by the end of the year and to 200 by the end of President Bolsonaro's four-year mandate.
Ms Sales, though, admits that some of her colleagues walked away, unhappy with the police presence in the school.
The assistant secretary of education for Brasília, Mauro Oliveira, says the controversial move was necessary. "We're talking about vulnerable schools, we're talking about drugs inside, teachers being threatened, so we need to go back to basics."
"As a democracy we should understand and do what the majority wants. People wanted a school that could offer more discipline and more safety for the kids," he explains.
But Jair Bolsonaro's focus on education is not just focussed on public security. He has also called for an end to what he has called "indoctrination" by left-wing teachers.
In the week he was inaugurated in January, he tweeted about his desire to "tackle the Marxist garbage in our schools head on". He added: "We shall succeed in forming citizens and not political militants."
He has taken aim at one of Brazil's most famous educationalists, Paulo Freire, an advocate of teaching critical thought in schools.
President Bolsonaro thinks Mr Freire, a socialist who was briefly imprisoned during the military dictatorship of 1964-1985 and who died in 1997, has played too influential a role in Brazilian education.
The president threatened to "enter the education ministry with a flamethrower" to remove Mr Freire's ideals.
Miguel Nagib thoroughly backs President Bolsonaro's aims. He founded Escola Sem Partido (Portuguese for School Without Party), an initiative to stamp out party politics from the classroom.
Mr Nagib blames the left-wing governments of Luiz Inácio Lula da Silva and Dilma Rousseff for what he says is the "indoctrination" of Brazilian students.
"When teachers are sympathetic to one party or another and promote that ideology, they're creating an imbalance in democracy," he argues.
He concedes that there are teachers on the right who use classrooms "for ideological means" but, he says, "they're snipers, they work alone".
"The party politics in Brazil came with the Workers' Party," he says of the party which governed Brazil from 2003 to 2011.
'An enemy that doesn't exist'
Many say that this attitude is a sign of the creeping conservatism in the Bolsonaro administration.
"It's important for the government to have an enemy to fight," explains Mauricio Fronzaglia of the Mackenzie Presbyterian University in São Paulo.
"They've created this caricatured vision that schools and universities are spaces to share Marxist ideas that need to be defeated. It's not true but it's a way of retaining the support of its voters."
The government has vowed to revise sex education in schools and there has also been talk of removing discussions about LGBT rights, gender violence and feminism.
Just a few weeks ago, the then-education minister, Ricardo Vélez, who has since been fired, suggested textbooks should be changed to deny the 1964 military takeover was a coup. Mr Bolsonaro has long defended the military's role, arguing it saved Brazil from communism.
"Once you start revising those political moments, valuing acts of violence and repression, you have to ask, what does this say about society?" says Cândido Granjeiro, president of the Brazilian Association of Textbooks.
"There are signs this government wants very specific content, to impose their way of doing things. That's something we've not seen before and it worries us."
At the Amorim Lima school in São Paulo, things could not be more different. The teachers greet the students with a kiss, sit on the floor for some of their lessons, and students have more freedom in how they learn.
Unsurprisingly, people disagree with Mr Bolsonaro's view of indoctrination. "We need these open spaces to talk," says Principal Ana Elisa Siquiera.
"What the government is trying to do is impose a doctrine, because they aren't letting people debate, discuss and believe in other things. Why should I only believe what the government is saying? They want to stop people from thinking. It's a total step back."