A former Cambodian sex slave, Somaly Mam, who has rescued thousands of women forced in sexual slavery, is now seeking the Sydney students' support in bringing an end human trafficking across South East Asia.
It wasn't an average lesson at 125-year old Abbotsleigh on Sydney's North Shore.
Hundreds of students from state and independent schools gathered to hear the story of Somaly Mam, who was sold into sex slavery when she was 12.
She now runs centres in Cambodia, Vietnam and Laos, rescuing women and children from slavery - one of them is just 3-years old.
Her own parents were killed in Cambodia's war. She lived on the streets until a man sold her to a brothel.
“You had to be in the brothel, you had to receive 20-30 clients a day, if you don't have it, they kill you,” Mam said in an interview to SBS.
She ran away after her friend was shot dead beside her. A foreigner helped her find a job. Later Mam decided to help others.
Somaly Mam has set up former slaves with microloans to finance craftwork and agriculture.
“It's so beautiful to see the girls come sad and then after a few months and years and years to see them get married to see them go to school”, she said
The United Nations estimates that human trafficking is a 32-billion dollar a year industry .
Earlier this week, Foreign Minister, Kevin Rudd, announced 7.5-million dollars to help South-East Asian countries train police to fight child sex tourism.
Somaly Mam estimates that she's helped about 7,000 women since starting her organisation 16-years ago.
But with 2.5 million women and children sold in the trade each year, she's seeking help from more fortunate young people who she says have the power to do something.
Students say they found her words confronting but inspiring.
“If every person made one change … we could change the future,” said Jessica Li.
Another student, Lucy Butcher, said that it made her and her fellow mates “realise there's a world beyond” them.
Abbotsleigh's headmistress Judith Poole says students need to know about human trafficking.
“This is reality, this is a global issue of massive proportion and it is important, our young people are ready for this,” she said.
Somaly Mam says that advocates fighting human trafficking need to become as motivated as the organised crime that runs it.