Changes

In recent years, Wu has witnessed the development of her students, who are no longer ashamed to ask questions about their physical changes or their confusion about close relationships with friends and parents.

"After we were given this semester's sex education textbook, one boy asked whether we could talk about the topics openly, because he thought some of the content might be too 'sensitive' for the older generation," she said.

Wu's daughter is a fifth grade student at Zhongguancun No 2 Primary School, which doesn't provide sex education classes and none of its teachers specialize in the subject.

Wu has been invited to give lectures at the school several times.

"It's not just migrant children; all children, and their parents need to know about this. Most parents have positive attitudes. It's very important to get parental support for sex education in schools. School time and parent-child time are both important. Only open attitudes will allow children to discuss sex with their parents," she said.

Removing taboos

Liu said children's cognitive abilities are different from adults, which is why the textbook uses illustrations of reproductive organs and emphasizes their scientific names.

"Kids will simply see all this as knowledge and science," Liu said, adding that studies in several countries have found no negative influences on children who received sex education at an early age.

"Taboos about sex result in concerns for some parents, and those taboos should be removed," she said. She also stressed the importance of the parents' role in sex education.

"Only by seeing the world from a child's perspective and throwing stereotypes away, will parents know how a child looks at and learns from the world."

Stereotypes

In January, the journal Science published research about gender stereotypes.

It found that intellectual ability emerges early and influences children's interests, indicating that stereotypes are endorsed by, and influence the interests of, children as young as 6.

In 2013, Liu's team launched a pilot sex education program in kindergartens based on guidance from the World Health Organization. Textbooks for children in kindergartens are still being written.

In 2015, a pilot project for junior high school students was also initiated.

"I wanted the textbook to not only be taken as a promotion of health-related information, but also to help children grow up with a positive life attitude and an open view of the world," Liu said.

Tang Yue contributed to this story