Back to the school, 开学 kāi xué

"开学", the Chinese word, has three interpretations: opening the school, starting to be a learner, and starting a semester. In daily life of the Chinese, it is used more at the beginning of the semester.

In mainland of China, there are two semesters in an academic year. 

The first semester usually starts on September 1st or an adjacent date. Then comes the winter vacation. The second semester usually starts in February or March depending on Lantern Festival that is on the fifteenth day of the first Chinese lunar month. When the second sememster ends, the summer vacation begins.