Children try to link parts of old-type telephones under the instruction of teachers on the 3rd Beijing Science and Technology Exposition for Juveniles in Beijing, August 3, 2006. Besides the introduction of popular science exhibitions from the United States and France, the exposition held various activities such as an exhibition of scientific and technological works created by teenagers of Beijing. (Xinhua Photo)

A student makes an experiment with a device on the 3rd Beijing Science and Technology Exposition for Juveniles in Beijing, August 3, 2006. The exposition, opened at the Military Museum on Thursday, provides youths with a colorful science world. (Xinhua Photo)

Children try to link parts of old-type telephones under the instruction of teachers on the 3rd Beijing Science and Technology Exposition for Juveniles in Beijing, August 3, 2006. Besides the introduction of popular science exhibitions from the United States and France, the exposition held various activities such as an exhibition of scientific and technological works created by teenagers of Beijing. (Xinhua Photo)

A middle school student shows a robot-controlled shadow play created by him and his classmates during the third Beijing youth science and technology exposition at the Military Museum in Beijing, Aug 3, 2006. (Xinhua Photo)