When is the right time to talk to your children about sex? An increasing number of Chinese parents, most of whom belong to the post-80s generation, choose to pay for a professional answer.

Pupils get a glimpse of life inside an artificial uterus in this photo taken on Feb 17, 2009, during a sex education course at the Science and Technology Museum in Zhengzhou, Henan province. [China Daily]

"I need professional help for my 6-year-old boy as the teachers in kindergarten have no idea about sex education," said a 30-year-old mother, who refused to be named.

"The teachers called me to the kindergarten when my boy said he loved a girl in his class, and my son refused to go to kindergarten after his teacher yelled at him for saying that," she said.

"I try to find information on sex education for children online. Not all of this information, however, is accurate," she said.

The mother is planning to pay for a four-hour course from Hu Ping, a sexologist who has given lectures on sex education in about 50 Chinese cities.

Every class is open to 10 children, and every child is asked to be accompanied by a parent, according to an online advertisement for the sex education class.