"Most people from my generation had to sit the college entrance examination, or gaokao, to enter university, the key to a stable, decent job. However, today's children have diverse choices as they grow up," says Liu.

"At this point, the parents have to help the children to examine their choices and explore more life possibilities," he adds.

The other child, Yu Lifan, has a father who has thrown himself into educating Yu to be versatile. The father says he himself was not competitive in sports during his early years, therefore, he is ambitious for Yu, hoping his son can perform well in the field.

The father-son relationship between them is typical in Chinese families, Liu says. And he uses more than three minutes in the documentary to depict how the son keeps hitting pucks into the net guarded by his father.