At a school hall in a deprived neighborhood of Colombia's capital, Bogota, a group of around 40 teenage boys and girls take turns to punch, slap, and kick each other.
It is role play, but scenes like this may be painfully familiar to some of the teens here, who have witnessed or experienced sexual abuse and domestic violence.
Students who have signed up for classes confront the traditional gender roles that pervade the macho society. Boys question what masculinity means – key to changing their behavior and curbing the widespread abuse of women in Colombia.
As electronic dance music blares out, the class encourages girls to say no to unwanted sexual advances and helps boys step into the shoes of the girls.
Sandwiched between two girls, one boy is poked and taunted as the girls grab his head and push it toward their groins.
"How did it make you feel being touched like that?" asks Jose Manuel Hernandez, a co-founder of The Men and Masculinity Collective, a Colombian charity that runs the program.
"It made me feel uncomfortable. I didn't like it. I couldn't get away," answered 13-year-old Nicholas Yecid.
Next, girls are paired with boys and told to yell "No" in their faces and push them away.
"The image many men have of their mothers is of a flawed, downtrodden, and submissive woman who's not autonomous and is incapable of saying no," said Hernandez, a psychologist.
"Here girls get a chance to say no and boys get to feel and see this, some for the first time."
In recent decades, progress has been made in Colombia and throughout Latin America on advancing women's rights.
Colombian women are now better educated, more of them have entered the workforce and politics, and new laws with tougher punishments for gender crimes have been introduced.
Colombia ranks 53rd out of 142 countries, above Latin America's leading economies – Brazil, Chile and Mexico – on gender equality, according to the World Economic Forum's 2014 Global Gender Gap Index.
But the socially conservative nation has made less progress on tackling violence against women, especially in the home.
There were nearly 76,000 reports of domestic violence last year, up nearly 10 percent from 2013, according to Colombia's National Institute of Legal Medicine and Forensic Sciences.
Such violence stems from Colombia's patriarchal and "macho" culture, say experts, which views women as inferior and tends to blame women for the abuse inflicted on them and to condone it.
Traditional gender roles, particularly in rural areas, in which a woman is expected to stay at home and look after the children, while the man is seen as the breadwinner who imposes his will, still hold sway.
The biggest threat to women and girls comes from relatives, stepfathers, and partners in their own homes. Eight out of every 10 cases of sexual assault against women and girls reported in 2014 took place at home.
Efforts to stem the abuse has focused largely on empowering girls and women to address the violence they face.
But the past decade has brought a growing recognition that boys and men must be in the forefront of combating gender violence, not just in Latin America but around the globe.
In the Kenyan capital, for example, every secondary school child will take part in a program that encourages adolescent boys to stand up against violence toward women.
In India, where a U.N. survey found that six out of 10 men admitted violence against their partners, some government schools run classes to confront traditional gender roles.
"Without involving men, you can't reduce pervasive patriarchy and cycles of violence. It means working with boys to change their views of masculinity, of what it means to be a man in our society," said Javier Omar, 62, a teacher who co-founded The Men and Masculinity Collective in 1996.
"Men are taught to be violent not caring. You need to make them discover a new type of man ... that leads to happiness, a better life, and becoming better fathers, lovers, and partners."
Working with 13- to 22-year-olds in poor communities, the army, and schools, the program involves role play, body painting, camping, dance, and theater.
Group discussions are often guided by male peers, giving boys an outlet for their feelings.
Research by a Colombian think tank, CorpoVisionarios, shows jealousy and perceived or real infidelity are often the triggers for men to beat up their wives and girlfriends.
Camilo Bohorquez, 22, says joining the collective 10 years ago gradually transformed him from an aggressive, macho man to a "new man."
As a child he would see his father abuse his young mother. He says he attempted suicide several times, led a life of crime, and felt social pressure to conform to macho ideals.
"Being a man in Colombia is difficult. In the neighborhood I live in your status as a man and how you stand out among other men is based on how much power and force you wield over others ... how many girls you have at your feet, how feared you are," said Bohorquez.
"I used to be that man. A bully."
Over the years, he learned to question machismo, something Bohorquez describes as a "toxic way of life that kills any affection."
"I can't deny this was very difficult. The hardest part of becoming this new man was letting go of my ego and accepting there were many women, and men, who were better at things than I was," said Bohorquez, who is now studying to be a psychologist.
A "new man" can cry, show affection, express his feelings, and say sorry, Bohorquez said. He can also find social status in ways other than through power and violence.
"Now my status comes from doing constructive and positive things for society," said Bohorquez with a beaming smile.
"[For me it's] through being an activist and showing other boys they can change and lead a happier life."
For The Men and Masculinity Collective, changing perceptions about manhood is as much visceral as it is an intellectual challenge.
At one workshop, Bohorquez and six other young men and women strip down to their underwear and start to paint each other's bodies using bright colors. They are asked to express their emotions by painting words.
"Harmony," "friendship,", "trust" they write across chests, backs, and thighs.
"For me changing machismo starts with your body," says Bohorquez, who is now standing naked.
"It's gratifying for me to use my body as a way of positive expression. It's about giving someone permission to touch your body with respect."
At his humble brick home perched on a Bogota hilltop slum, Bohorquez's mother, Nancy Herrera, says she felt emboldened after taking part in the workshops and seeing the positive changes in her son.
Herrera, 37, a basketball referee, says her husband used to control every aspect of her life.
"He expected me to just stay at home and look after our four children and sometimes forbade me from playing basketball," she said.
It was her son who encouraged her to stand up to his father.
"Camilo once told me: "Mummy you must be courageous and value yourself. You're free to lead your own life. I remember that day we cried a lot together," said Herrera, as her eyes welled up with tears.
"I've learned to love and know myself. Change is possible."
• Reporting by Anastasia Moloney, editing by Ros Russell. This article originally appeared on the website of the Thomson Reuters Foundation, the charitable arm of Thomson Reuters that covers humanitarian news, women's rights, trafficking, corruption, and climate change. Visit www.trust.org.