A teacher teaches students in a sex education class called "Traffic Lights for Our Bodies," at a primary school affiliated with the Shanghai University of Science and Technology, Oct 24, 2011. In the class, children are taught about their private parts, as well as how to protect themselves in accordance with rules described in the sex education book "Boys and Girls." This is the first sex education textbook to be introduced to pupils in Shanghai after numerous debates on early-childhood sex education in China. The book is expected to be introduced to students at 18 primary schools in the trial phase. [Photo/CFP]

Students embrace each other in a sex education class at a primary school affiliated with the Shanghai University of Science and Technology, Oct 24, 2011. [Photo/CFP]

Students cover different parts of a cartoon human body with red or green pieces of paper during a lesson in sex education at a primary school affiliated with the Shanghai University of Science and Technology, Oct 24, 2011. [Photo/CFP]

Students are taught to recognize reproductive organs and sensitive areas in a sex education class at a primary school affiliated with the Shanghai University of Science and Technology, Oct 24, 2011. They held up "red lights" or "green lights" when they see offensive or friendly gestures in pictures displayed by the teacher. [Photo/CFP]

Students raise their hands to answer questions during a sex education class at a primary school affiliated with the Shanghai University of Science and Technology, Oct 24, 2011. [Photo/Xinhua]