The Chinese government offers a few scholarships for polytechnic students, but they are distributed mostly based on grades, not financial need. Top students, often from more affluent families who could give them more academic support during their formative years, receive grants that cover up to three-quarters of their room and board.

Average students like Ms. Wu pay full cost and hear frequent complaints from their parents. “I tell my daughter to study harder so she can reduce the school fees,” Mrs. Cao said.

But studying is almost all that Ms. Wu does. She says she still has no boyfriend: “I have friends who have boyfriends and they argue all the time. It is such a hassle.”

The big question for Ms. Wu and her family lies in what she will do on graduation. She has chosen to major in logistics, learning how goods are distributed, a growing industry in China as ever more families order online instead of visiting stores.

But the major is the most popular at her school, which could signal a future glut in the field. That is a sobering prospect at a time when young college graduates in China are four times as likely to be unemployed as young people who attended only elementary school, because factory jobs are more plentiful than office jobs.

Ms. Wu realizes the odds against her. Among those who graduated last spring from her polytechnic, she said, “50 or 60 percent of them still do not have a job.”

Mrs. Cao is already worried. The family home across the road from the abandoned coal mine is starting to deteriorate in the wind and acrid pollution, and they have scant savings to rebuild it. Her husband has been able to move home after being hired at a new mine in Hanjing as a drilling team leader. The extra responsibility allows him to almost match his pay at the desert coal mine, but at his age carrying a heavy drill is becoming more difficult, and he won’t be able to continue doing hard labor forever. Their daughter is the parents’ only hope.

“I’ve only got one, so I have to make sure that one takes care of me when we get old,” Mrs. Cao said. “My head is killing me with thinking, ‘What if she can’t get a job after we have spent so much on education?’ ”