Yunnan province in southwestern China has one of the highest rates of HIV-AIDS prevalence nationwide. In one of its village, close to the China-Myanmar border, one man provides AIDS prevention and sex education classes to many children.

Deep in the mountains—with narrow, muddy, and rocky paths and only three hours walk to the border of China and Myanmar—the village feels like isolated from the rest of the world.

In the past two years, Dong Shican—the only school teacher in the village—cannot remember how many times he visited the parents of his students. His mission is to give new clothes and stationeries or ask drop-outs to come back to school. But in some visits, he need to walk eight kilometers just to reach one student’s house.

Most of the villagers live under the national poverty line. Having children to go to school is a big hurdle for most of the villagers. One eight-year-old girl has almost dropped out from school. But Dong’s frequent visit convinced her parents to continue her education.

A few students, with Dong’s help, were able to go out of their village and continue higher education. But that is 45 kilometers away.

“Now we are very poor, but later when our children grow up, with the education they have, they can help us. And I hope they have work in the future,” a student’s father said.

Dong said the first time he came here, the school had only one classroom. No toilet or cellphone signals. He was the only person who lived here.

Living in such conditions is not that new to Dong, as he himself was raised in a rural village. But the poor situation in the village shocked him.

“Teaching students had changed my mind, so I stayed in school. Many of the previous teachers here were junior high or high school graduates. As teachers here change frequently, students have had bad grades. But now, they are better,” Dong said.

In 2014, the school received financial support from the local education department and an organization called “AIDS Prevention Education Project for the Chinese Youth.”

Now it has a new toilet, one new classroom, and a kitchen where students who live far away can cook. The organization is also providing sex education and AIDS prevention classes.

“We teach first graders the differences between boys and girls, and that they need to protect their private body parts. We teach them of what to do when they are sexually assaulted,” Dong said.

There are 70 students in the school, from kindergarten to third grade, ranging from six to fifteen-years-old. Sex Education and AIDS Prevention is crucial for students like these who live in poverty.

“The county has the longest borderlines with Myanmar. It has many ethnic groups, and according to their customs, many have early sexual behavior and get married between the age of 12 and 15. Their parents have no knowledge of how to protect their children, so many girls get pregnant even if they are very young,” said Yang Chunyan, director of AIDS Prevention Education Project for Chinese Youth, Ying Jiang County Office.

Families all remember Dong Shican, as he is the only teacher who stayed in the mountain for as long as he could and passed on knowledge to their children.