hildren experience acoustics devices during a science popularization activity in Langfang, north China's Hebei Province, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)

A staff member (1st L) introduces deep-sea organism to visitors at Shanghai Natural History Museum in east China's Shanghai, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)

Children and a volunteer make a model of science popularization in a community of Hefei, east China's Anhui Province, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)

A staff member makes pottery during a science popularization activity in Hexi District of north China's Tianjin, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)

A child experiences a mechanics game during a science popularization activity in Kunming, southwest China's Yunnan Province, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)

A science popularization volunteer interacts with children in a community of Hefei, east China's Anhui Province, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)

Children experience a science popularization equipment during an activity in Langfang, north China's Hebei Province, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)

Citizens watch robot dancing performance during a science popularization activity in Kunming, southwest China's Yunnan Province, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)

Children look at a deep-sea exhibit at Shanghai Natural History Museum in east China's Shanghai, Sept. 15, 2018. A variety of activities were held across the country to greet the annual day for science popularization in China. (Photo: Xinhua/Wang Xiao)