BEIJING — On a bitterly cold morning this month, Wang Fuman, 8, set out for school as he usually did, walking 2.8 miles through mountains and streams until he reached the warmth of his third-grade classroom.

When Fuman arrived two hours later, his classmates erupted in laughter. The freezing temperatures had covered his hair, eyebrows and eyelashes with frost, making him look like a snowman. His cheeks were chapped and bright red.

Fuman’s teacher at the Zhuanshanbao primary school, in the southern province of Yunnan, snapped a photograph and posted it on WeChat, a popular Chinese messaging app. Soon, the boy became an internet sensation, hailed by commenters as a symbol of the raw determination of rural residents, who make up about 43 percent of China’s population.