Children greet 2018 National Science Day across China

A man shows how to operate a hand-driven generator to his child at the People Square in Shijiazhuang, north China's Hebei Province, Sept. 15, 2018. Various activities are scheduled to be held from Sept. 15 to Sept. 21 across China to greet the 2018 National Science Day held each year. (Xinhua/Zhang Xiuke)