On Thursday, the panel of experts suggested that low building standards may have cost the lives of the children.
Ma Zongjin, chairman of the committee, said poor quality materials and inadequate support for large classrooms were likely reasons that led to more than 1,000 schools to collapse in the quake.
"In recent years, a lot of school buildings have been built in China and in this process of rapid development, some problems may exist," Ma, a geologist, said in Beijing.
"The structure of the school buildings may not be reasonable enough and the related construction materials may not be strong enough."
Ma said a key problem was the lack of reinforcement in large classrooms supported by columns that could not withstand major earthquakes.
The 30 engineers and building experts assigned to the disaster zone have also raised questions about the quality of construction and compliance to building codes.
The government, along with the probe, has vowed strict punishment for bad construction but no attempt has been made to hold anyone publicly accountable yet.
The issue has become politically sensitive for the Chinese government, with parents of dead children staging protests demanding investigations into why schools gave way when other buildings remained standing.
In many areas schools were the only buildings to fully collapse and experts say China's problem, similar to that in many other parts of the world, was a lack of government commitment to safe schools.
China has said that about 7,000 classrooms were destroyed, but has so far not released a tally of how many schoolchildren died in the quake, the country's worst disaster in 30 years.