Uniformed pupil volunteers explain traffic signs to others in Yinchuan, capital of northwest China's Ningxia Hui autonomous region, July 5, 2012. As the summer vacation of the pupils starts, traffic policemen came to Manchun Primary School in Yinchuan on Thursday to hold a lecture on safety education for children of migrant workers. Policemen and volunteers explained traffic signs and rules to the pupils.[Photo/Xinhua]