Being one player short used to be the biggest hurdle preventing Liu Xiurong from playing mahjong.

"You cannot do anything but wait for a fourth player or persuade a passer-by to come into the game," said the retired woman in her 50s.

Liu retired several years ago and with her only son studying in East China's Fujian province, mahjong has been one of the few entertainments to distract her from loneliness.

But now the struggle to find other players is a thing of the past because she can pick up the game anywhere and anytime, with her newly bought laptop.

"By clicking the mouse I can easily get in an online room for the game," said Liu, who has just learned the online game through a computer class designed for the empty nesters, or senior citizens in a family with no children around to relieve their solitude.

The class was organized by Sun Xia, a resident of the Fuyuyuan community in Beijing's Huairou district, who said about 40 such empty nesters have registered for the class since last year.

"Most of the senior people coming to our class are living by themselves or with their partners, with no daughters or sons around them," she said. "Introducing them to the online world might bring them closer to their children and relieve them of some isolation."

Liu said her life has been greatly improved after learning video chat online, which she said might be the "greatest invention ever".

"I talk to my son 'face to face' everyday after dinner, despite him being thousands of miles away," Liu said. "It is as if he was still living with me right next door.

"My son was surprised and glad to see me capable of chatting with him online," she said.

Liu said she is learning to "weave a scarf", a Chinese saying for using a micro blog.

"People say there are many life tips and recipes for healthy diets on there, and I'm going to dig them out," she said.

According to Sun, as more young people are studying or working away from their families, increasing numbers of elderly people are left at home, retired, and with an abundance of spare time. She said it was a growing social phenomenon in China.

"Many children have either gone abroad or are busy with work with little time to visit their parents, let alone take care of them," she said.

Cai Yaling, a retiree and the volunteer teacher of the computer class, said she was glad to see many of her students surfing the Internet or communicating with their children online while several months ago they did not know how to turn on a computer.

She said it was difficult for seniors to learn new things due to their poorer memories and hearing.

"Most of the students in their 50s to 70s learn things so slowly but forget so fast," Cai said jokingly. "It might take them two months to memorize what the young people can learn in two days," she said.

"For me I need to repeat the things again and again, class after class, to help them memorize."

But Cai said the students have the time to dedicate to learning, and since the skills can allow them to stay in touch with their children, they are very motivated.

The class, held every Wednesday and Friday afternoon from 2 pm to 4 pm, is attracting more and more senior citizens.

"I'm introducing some of my neighbors and friends to the class because they are jealous of me talking to my son online," Liu said.

"Maybe we will have to share the 15 computers in the classroom in the future," Liu said.

However, Liu has one concern.

"I heard people can get addicted to the Internet when surfing on it for too long," she said. "I'm a little bit worried since I can spend seven to eight hours a day sitting in front of a computer to practice typing or play mahjong."

She has also bought a new laptop since she had to scramble for the only computer at home with her husband, who also attended the computer class in the community.

"One computer for each and no more quarrel," she said. "Hopefully neither of us will get addicted to the Internet, which sounds horrible."