In the United States we have the ACT or the SAT. In China, they have the equivalent in the Gaokao.
During the final year of high school, or earlier if they are so inclined, Chinese students must take this test if they plan to attend to college. For many rural families, this is the only opportunity their child will have to better their life, leading to extreme pressure to do well.
Apparently this is an extremely common practice during crunch time and the only reason this story made the news was because the teachers brought the IVs into the classroom.
Normally students would have to leave school grounds in order to get amino acid injections from a local clinic before returning to class, cutting into valuable studying time.