Zhang Wei holds her son,Tutu, while giving a lecture at Hanshou No. 1 high school in Changde, Hunan province on May 7, 2015. [Photo/CFP]

Zhang Wei is a chemistry teacher at Hanshou No. 1 high school in Changde, Hunan province. Her three-year-old son, Tutu, was diagnosed with leukemia in 2014 and has undergone chemotherapy since.

Zhang and her husband have spent all their savings for Tutu's medical treatment, but they cannot afford the 700,000 yuan ($112,000) it will cost to get Tutu a bone marrow transplant. Her husband is a middle-school teacher in a far-away remote town and cannot regularly return home, which leaves Zhang to take care of Tutu on her own.