Chinese officials, facing a barrage of questions from bereaved parents and angry citizens, say they will launch an investigation into why so many schools were toppled by last week's earthquake.
Officials said that at least 6,898 schoolrooms had collapsed in Sichuan province, where the quake was centered.
"If quality problems exist, we will definitely punish those responsible severely and give the public a satisfactory answer," said Han Jan, director of the Ministry of Education's development and planning department.
There are more than 418,000 elementary, middle and high schools in China, most of them in the countryside. The government has spent more than $2 billion in the last several years to renovate dilapidated rural schools.
But well before the magnitude 7.9 quake buried thousands of children in dozens of flattened schools, there was a long list of schools devastated by smaller quakes in China.
Since 1990, when China's seismic building codes were already established, thousands of schools have collapsed or sustained major damage, primarily in the countryside, according to research by Gao Jianguo, a professor at the Institute of Geology under the China Earthquake Administration in Beijing.
In 2003, the latest year for which Gao compiled data, earthquakes destroyed or damaged more than 2,300 schools that served 425,000 students. Gao's report didn't chronicle deaths and injuries, or the substantial toll to schools from other disasters such as heavy storms and flooding.
In an interview, Gao said one major reason schoolhouses in rural China are vulnerable is that they have larger rooms lacking interior roof supports to accommodate class sizes of 70 to 80 students.
"So if the construction doesn't meet standards, or cement quality isn't good, or the steel isn't thick and the beam not strong, then they are more likely to collapse," he said.
At Juyuan Middle School near Dujiangyan, just south of the quake's epicenter, scattered classroom chairs sit in the open sports field where students huddled the night of the earthquake, fearful of aftershocks. The teachers' rooms held up well. But the four-story main building was nearly destroyed, with about 900 students lost. One small four-story section remains, resembling a lighthouse in size and appearance, of what was once a large complex of classrooms.
"My 15-year-old nephew was found dead," said Wang Hong, a 41-year-old restaurant worker. "We really wonder about the construction quality."
In questioning the structural safety of schools, Wang and many other Chinese touched on thorny issues that have troubled Chinese leaders for years: the wide income gap between rural and urban centers; the competence and integrity of local officials; and a lack of funds for basic education in a country that has spent hundreds of billions on roads, bridges and other infrastructure.
Wang Zhenyao, Beijing's disaster relief director at the Ministry of Civil Affairs, said during a news conference last week that schools weren't the only buildings that collapsed. He said the Civil Affairs bureau offices in Beichuan County also came down in ruins.
"Government buildings are not all that solid," Wang said.
Countless houses, apartments and other properties were destroyed. But in some places, schools were the only buildings that tumbled.
In a northern rural district of Chongqing, about 200 miles from the epicenter, a four-story building collapsed at Center Elementary School, killing at least five students, according to local media accounts. Yet the apartments and houses behind the school were still standing.
The brick and concrete Center school building was constructed in the 1990s, later than the houses behind it, by a private contractor who apparently has gone into hiding, according to Chongqing Evening News.
By one self-reported assessment provided by the Ministry of Education, about 6.5% of the rural primary schools in 2006 were considered weifang -- dangerous houses -- about double the rate of urban schools.
The actual number of unsafe schools is much higher. Lianshan Complete Primary School in Shaanxi province isn't listed as a dangerous school. But its eight classrooms for 314 students and 20 teachers are in brick buildings with no concrete beams or pillars, said headmaster Chen Yudong.
Although the school is in a seismic zone, "the government's never come to inspect our facility about earthquake resistance," said Chen, who has been at the school since 1985.
Du Xiuli, dean of the College of Architecture and Civil Engineering at Beijing University of Technology, said that if schools in Sichuan province were built according to current code for that area, a magnitude 7.9 quake would have caused damage but shouldn't have led to their collapse.
He said some of the schools might have been built before the seismic code took effect, and construction quality at others might have been poor.
Li Yadong, director of the China Youth Development Foundation's Hope primary school department, a nonprofit group that has supported school construction in remote areas, said there were no reports that any of the 170 Hope primary schools in Sichuan province had collapsed. He said the primary schools it helps fund typically cost between $70,000 and $115,000, and the design and construction are supervised closely.
But Bing Bing, a volunteer teacher in Guizhou province and organizer of a teachers union that has helped build rural schools, said the union's facilities run only about $16,000 each.
Typically they are single-story structures with two classrooms, one office and a warehouse, she said.
"We have never thought about earthquake resistance before," Bing said. "We were thinking about the most urgent needs, that is, to let those kids have a school building first."
Times staff writer Mark Magnier in Dujiangyan and Cao Jun in The Times' Shanghai Bureau contributed to this report.