As China's remarkable export expansion loses altitude, containers once hoisted around busy ports have found an additional use.

In a northeast Beijing suburb, five colorful freight containers have been converted into classrooms to accommodate after-school care for children of migrant workers.

Each weekday at 4:00 p.m., about 100 pupils from schools in the area hurry into these renovated containers to do their homework. After a salvo of noise and excitement, they quiet down and bury themselves in their exercise books, aided by volunteers.

The containers are located in Heiqiao Village, a dilapidated community surrounded by a railroad track used to test China's high-speed trains.

Unlike the nearby high-rise cityscape, Heiqiao has become a forgotten place, isolated by the railroad surrounding it. But a large number of migrant workers still crowd into the area since rents are relatively low.

However, having no suitable place for their children to do homework has caused much anxiety for migrant worker parents who barely have time to take care of their children.

In recent months, the demolition of a dozen temporary schools for migrant children has already raised much concern among the public. Some of the schools were closed down because they didn't meet academic or construction standards. More than a few were closed because the land was pegged for other purposes.

In fact, it was the closing of so many schools that lent inspiration to Han Kefei, general manger of Compassion for Migrant Children, a Beijing-based nonprofit organization. Han proposed using containers as an after-school study site.

Han leads a staff of 20 to operate the Heiqiao study center. As many as 150 volunteers helped get the facilities ready. They cut doors and windows in the container's iron surfaces and outfitted them with tables and chairs to serve as makeshift classrooms.

Han Kefei told Xinhua, "The containers are movable. They can go with the migrant children, and more importantly, the facilities can be easily relocated without damage."

Beijing has seen a rapid expansion of migrant workers in the past decade. The schooling of their children poses severe challenges to the city's strained education resources.

Now Beijing is home to about 478,000 children of migrant workers, about 4.6 times more than in 2000, according to statistics from the Municipal Education Bureau.

"Unstable schooling, as well as the lack of space for after-school activities and absence of tutorial help have all dented the competitiveness of migrant workers' children in comparison with children born in the city," Han said.

Zhang Xichao, a college volunteer, nudged a boy who was thinking hard about his English homework. "Pay attention to the third person singular form," Zhang said.

He was working inside a yellow container stacked on a green one. Different grades are assigned to containers with different colors. Only the yellow one for fifth graders is on the second floor.

Zhang's task is to offer tutorial assistance to fifth graders and maintain order during breaks. In front of the wire-enclosed container area is a multipurpose court where children can play basketball, football or skip rubber bands.

The container center has gained increasing popularity in the community as migrant children in primary school also use it as a place to play. Their schools are usually too cramped to have a playground.

"My boy loves this place, and indeed he has nowhere to go after school," said a parent, "And it's all for free. That's wonderful."

Han's team strives to show care for the children, but also tries to build children's self-reliance.

The center's guideline requires volunteers to "...gently discourage the child from sitting or lying in your lap."