"When her parents told her their decision to work in the city, she was extremely frightened. She was afraid that they would really leave her forever. She couldn't imagine what life would be like," said Zhang Ning, a volunteer from Communication University of China.

Zhang went with her volunteer team to Xuanhan county, in Dazhou, Sichuan province this summer, where many children are left behind.

According to scholarly definitions, left-behind children are those whose parents seek long-term jobs as migrant workers in urban areas. There children are therefore left behind in the countryside and cared for by relatives – often grandparents. They are separated from their parents for many years.

A recent study conducted by China Women's Federation shows that there are about 58 million left-behind children in China, and 40 million are under 14 years old.

It's the fourth summer volunteers from Communication University of China have come to the town where they established volunteer program in 2007, teaching left-behind children and doing research.

China Daily brings you Zhang Ning's very special encounter with those children.

Video: Feng Xin and Zhang Yu

Producer: Flora Yue