A volunteer hosts a knowledge contest on garbage classification for pupils at the Juyuan Primary School in Qingdao City, east China's Shandong Province, Dec. 18, 2019. Youth volunteers for social service from the Qingdao Zhanqiao Bookstore launched a scientific information outreach program at the Juyuan Primary School Wednesday. Through video clips, knowledge contests, short dramas and amusing games, the volunteers attempted to help the pupils better understand the necessity of garbage classification as well as the importance of environmental and ecological protection. (Xinhua/Li Ziheng)