Prophylactic benefits

Educational material about female sexual organs is limited to an eighth grade biology book, so Nan also teaches the girls about menstrual hygiene and protecting themselves when coming into contact with young men. "Students have now become more willing to share their experiences about physical changes in adolescence. They openly discuss things outside of class," Nan said.

Shan Rong said previously she only talked about menstruation to close friends and girls experiencing it for the first time.

"Now, I don't feel ashamed when overhearing boys whispering things about girls menstruating," she said.

"It is a normal change in our bodies and there's no reason to be embarrassed. Sometimes, I even tell them not to be so serious about it."

Nan said children who have received sex education are less likely to encounter risks. "The more mysterious sex is, the more likely it is to lead to bad outcomes for children because of their curiosity," she said.

The school plans to open a sex education class for boys and encourage male teachers to instruct them on physiology and psychology.

Lu said: "Correct concepts and knowledge of sexual and reproductive health can affect their generation."

Zhai Anru and Li Yinglian contributed to this story.