Students demonstrate craftwork produced out of recycled materials during an environmental awareness activity marking Earth Day, which falls on April 22, at the Second Primary School in Donglin Township of Huzhou, east China's Zhejiang Province, April 19, 2019. (Xinhua/Xu Yu)

Students produce craftwork out of recycled materials during an environmental awareness activity marking Earth Day, which falls on April 22, at the Second Primary School in Donglin Township of Huzhou, east China's Zhejiang Province, April 19, 2019. (Xinhua/Xu Yu)

A student produces craftwork out of recycled materials during an environmental awareness activity marking Earth Day, which falls on April 22, at the Second Primary School in Donglin Township of Huzhou, east China's Zhejiang Province, April 19, 2019. (Xinhua/Xu Yu)

A teacher and students produce craftwork out of recycled materials during an environmental awareness activity marking Earth Day, which falls on April 22, at the Second Primary School in Donglin Township of Huzhou, east China's Zhejiang Province, April 19, 2019. (Xinhua/Xu Yu)

Students produce craftwork out of recycled materials during an environmental awareness activity marking Earth Day, which falls on April 22, at the Second Primary School in Donglin Township of Huzhou, east China's Zhejiang Province, April 19, 2019. (Xinhua/Xu Yu)