In Truong To high school on the outskirts of Ho Chi Minh around 50 adolescent girls discussed on Monday the risks of teenage pregnancies, sexual abuse and comparing the signs of puberty in boys and girls.
A few minutes later, the teacher instructed them in self-defense techniques, which the students practiced in pairs over the next half hour, taking turns to play the aggressor and the victim.
Such scenes are, however, an exception in Vietnam, where sex education is not part of the core curriculum and is often clubbed in with other subjects.
The session in Truong To was organized by the Alliance Anti-Trafic nonprofit, a pioneer in sex education in Vietnam and which, since the start of its program in 2008, has trained some 60,000 adolescents.
The nonprofit advocates that sex education be made compulsory in schools before 2019 to bring down sexual abuse and unwanted pregnancies.
Ngan Ta, who is in charge of the project, said progress was slow owing to a shortage of resources, a difficulty in training teachers and a conservative society that fears children might start learning about sex too early.
However, ATT has received a positive response from parents, who are relieved to let the schools deal with sex education.
In ATT's classes, students openly discuss contraceptive methods, unwanted pregnancies and abortion, a problem Vietnam has been failing to address for years.
Vietnam has the highest abortion rate in Asia (an average of 2.5 abortions per woman), including a high rate of abortion among teenagers and young women: 8.4 percent of the women between 15 and 24 years old have had at least one abortion, according to official statistics.
Ta asserts sex education is important to prevent sexual abuse, which has been growing in the country.
According to Vietnam's Ministry of Labor, Invalids and Social Affairs, at least 1,2000 cases of sexual abuse are recorded among children every year.