In this file photo taken in May 1952, children attend a drawing activity at Guangzhou Municipal Nursery in Guangzhou, south China's Guangdong Province. China celebrated International Children's Day on June 1, 2019. These file photos recorded how Chinese children spent their childhood in nurseries and kindergartens dozens of years ago. (Xinhua/Wen Wei Po)

In this file photo released on Dec. 19, 1959, Chen Yuying (L), a kindergarten nurse, helps children wear winter clothes in Nanjing, east China's Jiangsu Province. China celebrated International Children's Day on June 1, 2019. These file photos recorded how Chinese children spent their childhood in nurseries and kindergartens dozens of years ago. (Xinhua/Wang Wenhua)

In this file photo taken in 1952, children of a nursery take care of silkworms in Beijing, capital of China. China celebrated International Children's Day on June 1, 2019. These file photos recorded how Chinese children spent their childhood in nurseries and kindergartens dozens of years ago. (Xinhua)

In this file photo released on Dec. 19, 1959, Wu Xiulan, a kindergarten teacher, washes a child's hands in Nanjing, east China's Jiangsu Province. China celebrated International Children's Day on June 1, 2019. These file photos recorded how Chinese children spent their childhood in nurseries and kindergartens dozens of years ago. (Xinhua/Wang Wenhua)

In this file photo released on April 4, 1960, Li Changlan (1st R), a kindergarten teacher, measures children's heights at Xinjiekou Guozishi Kindergarten in Beijing, capital of China. China celebrated International Children's Day on June 1, 2019. These file photos recorded how Chinese children spent their childhood in nurseries and kindergartens dozens of years ago. (Xinhua/Yang Zhanhua)

In this file photo released on June 6, 1955, a group of children play with wooden toy wagons at Guangzhou Municipal Nursery in Guangzhou, south China's Guangdong Province. China celebrated International Children's Day on June 1, 2019. These file photos recorded how Chinese children spent their childhood in nurseries and kindergartens dozens of years ago. (Xinhua/Li Jiawei)

In this file photo released on May 25, 1963, children of Yanji Municipal Nursery rehearse for an upcoming song and dance gala in Yanji of Yanbian Korean Autonomous Prefecture, northeast China's Jilin Province. China celebrated International Children's Day on June 1, 2019. These file photos recorded how Chinese children spent their childhood in nurseries and kindergartens dozens of years ago. (Xinhua/Liu Entai)

In this file photo archived on Nov. 16, 1981, a group of toddlers take part in an indoor physical exercise at a nursery in northeast China. China celebrated International Children's Day on June 1, 2019. These file photos recorded how Chinese children spent their childhood in nurseries and kindergartens dozens of years ago. (Xinhua/Liu Entai)