'Portable' expenses

He suggested making compulsory education expenses "portable" to solve the problem.

"In this way, the inflow of migrant children won't pose great challenges for local governments, and these cities will become more open to migrant children."

The central government has already made moves in this direction. According to a notice released by the State Council, China's cabinet, in December, a unified national standard will be established to cover the cost of compulsory education, and the authorities will ensure that schools are reimbursed, no matter where the students live and study.

However, Xiong believes that a move away from controlling population numbers by restricting children's educational opportunities could be an equally effective measure. "Irrespective of the solution, we must ensure that every child has the right to receive compulsory education," he said.

Qin said that in the past two years Beijing Zhiquan School has made efforts to reverse the decline in student numbers. It has started classes about traditional Chinese culture, and many of the attendees are children from higher-income white-collar families. "Many of these schools will either have to change or die," he said.

Zheng, of the Dandelion School, said the departure of some of the migrant workers would not have a significant impact on the school: "No matter how modern a city becomes, it still needs people to work in the low-end service industries. It's impossible that all the migrant workers will leave Beijing."

By the end of the year, with the aid of donors and the local government, the school will move to a new 1-hectare site near its current premises that will accommodate more than 800 students in 18 classes, compared with about 500 now.

"Our goal hasn't changed - we will continue to provide quality education for children from the poorest families," she said.