BEIJING — The young survivors of the Sichuan earthquake marked Chinese Children’s Day yesterday still living in tents and studying in makeshift schools in refugee camps.

June 1, usually a chance for children to have a day off and an extra helping of presents, this year became an opportunity for the authorities to show that they cared for those who were the most visible victims of the disaster.

It is now estimated that more than 11,000 schoolchildren and teachers lost their lives when their classrooms collapsed in the quake three weeks ago. Parents used the opportunity of the special day to hold vigils and protest about the poorly-constructed school buildings they say were responsible in many cases. “This is all because of corruption!” shouted a grandfather standing near a pile of rubble decorated with photographs of children where their school once stood in the town of Wufu, north of Chengdu. “They didn’t spend enough on the school and now our children are dead.”

Government inspectors are investigating claims that many of the schools were destroyed because money for good quality concrete was skimmed off by corrupt officials. President Hu was shown by state press outlets talking to children on a visit to Shaanxi province, which neighbors Sichuan and which was also badly affected by the quake.

He told the children of Jinshansi village: “I promise you to help you build a new school. You will be sure to have a better classroom.”

One major threat may be lifted today after the completion of a drainage channel to remove water from a lake formed above the town of Beichuan by a landslide. More than 1 million people have been on alert to leave the valley below in case the natural dam formed by a landslide after the earthquake burst under the pressure of the water.

Meanwhile, rescuers were searching for a helicopter that crashed with four crew while taking 10 earthquake survivors to hospital.

[Bloomberg News reported yesterday that a Chinese military helicopter carrying earthquake victims crashed with 14 people on board, underscoring the difficulties relief efforts face even as rescuers found two miners who’d been stranded for 19 days.

President Hu of China, who is visiting east-central China’s Shaanxi province to direct relief operations, ordered an immediate search for the helicopter, the official Xinhua news agency said. It crashed Saturday afternoon after running into turbulence in Sichuan province’s Wenchuan county, one of the areas worst hit by the May 12 quake, according to Xinhua.]