The so-called fragment teaching is relative to a complete classroom teaching. Generally speaking, a part of a class is intercepted, and the teacher's teaching time is roughly limited to less than ten minutes. In other words, fragment teaching is only a link in the process of teaching implementation, and the instructor expresses his teaching thoughts, teaching ability and teaching basic skills by completing the prescribed teaching tasks. Fragment teaching is different from normal classroom teaching. The former is illusory, and its function is teaching and research or evaluation. Participants are leaders, peers or experts, and judges. The latter is holistic and practical, and its function is to "preach, teach and dispel doubts", and its audience is students. Fragment teaching is also different from teaching fragment. The former is based on the specified "fragment", and the teaching design and implementation process are independent. The latter only intercepts part of the records from the complete classroom teaching process after class. Fragment teaching is more different from "lecture". The former is to implement (or simulate) classroom teaching, while the latter just talks about classroom teaching. Fragment teaching has strong independence, but it is closely related to lectures. In many teaching and research activities and evaluation of teaching level, teachers are often required to give lectures first, and then carry out fragment teaching on the basis of lectures, so as to organically link teaching ideas and their theoretical basis with teaching implementation, so as to overcome the disadvantages of teaching theory being divorced from reality.