Like millions of Chinese children, 16-year-old Song Yuedong sees his parents just once a year.
As China's army of migrant workers toil to build their nation's future, children like Song live with relatives, often knowing their parents only as voices on the end of a phone.
Shy, wearing an American basketball tee-shirt and sporting the fuzzy beginnings of a mustache, Song looks like any teenager anywhere in the world.
He lives with his grandparents in the farming town of Mingchuan in Anhui province, one of China's poorest regions which since the 1970s has been a major source of the cheap labour that has fueled the nation's explosive growth.
More than 130 million people like Song's parents have left their farms for work in China's cities -- in their case a factory in neighbouring Jiangsu province.
They come home once a year for the Lunar Chinese New Year holiday, the traditional season for family reunions.
"When they come back, I am very happy because I can finally see them after such a long time," Song said.
Grandfather Song Yequan, 69, who has an optimistic air and speaks with a thick local accent, said all his four sons have left the farm and are making enough money to ensure his grandchildren will have a better life.
"Two of my grandchildren are going to school, they have grown up at my side, I have fed and clothed them," he said. "Their parents pay all the expenses."
Song insists his grandson has not suffered from his parents' absence.
But others are not so lucky, with many plagued by psychological problems stemming from the separation from their parents.
Social scientists raised the alarm years ago and have coined a special term for such children: "liushou ertong" or "the children left behind".
They tend to be raised by their mothers or, if she has gone too, by other relatives. Either way, the children tend to be spoiled and many are vulnerable to violence including rape because they lack parental care, experts say.
"Psychological or emotional problems are more and more common because under normal conditions, children need to be with their parents to communicate with them," said Duan Chengrong, a specialist on the issue at People's University in Beijing.
"They are separated and they cannot communicate. Some of the children have not seen their parents for five, sometimes 10 years. This is a serious problem in the development of the child."
Duan said the number of such children has exploded, with latest figures showing 58 million in this situation in 2005, up from from 23 million in 2000. Half of them are missing both parents.
In Anhui, authorities have taken steps to defuse what experts say is a social time bomb with the introduction of programmes aimed at dealing specifically with the problems of the 'liushou ertong'.
In 2004, Song's school -- where about 14 percent of the 400 children are 'liushou ertong' -- became one of the first in the province to introduce these special programmes.
The students benefit from special care and have professors who are designated as "interim family heads".
Grandparents are offered training so they can help children with their homework, and the children can call their parents if they feel the need.
"Before we had a lot of problems with the students," said Xie Xinzheng, the headmaster at Song's school.
"But since we put the programme in place, the grades of 'liushou ertong' have gone up and the problems that we had with them have gone down."