Out in the open

Yang teaches adolescent psychology and Nan Yuehong, a biology teacher at the school, has been responsible for the physiology side of the classes for the past 10 years.

"The class is more popular than we thought. While adults usually avoid talking about the issue, students are curious and crave this kind of knowledge despite their shyness in class," said 36-year-old Nan.

When Nan demonstrated the correct way to use sanitary napkins, girls lowered their faces and blushed. "The more shy a student appears, the more it proves it's necessary to popularize knowledge about hygiene and sex," Nan said. "They need to know more about the issues to protect themselves."

Over a semester, the students take about six classes, usually in the afternoon. If the classes clash with other subjects the girls can take them during the lunch break.

Lu Yongming, the school's vice-principal, said Yang started the classes because she was concerned about her students' psychological states when it came to sex education. "Yang found some puppy love and online crushes among the girls. In response to their parents' concerns, and to avoid potential risks, she brought up the idea," Lu said.