In the educational community, the discussion of "teaching/education returning to life" still remains confusing and contentious. Therefore, it is of great importance both in theory and practice to explore the relationship amongthe teaching world, life world and science world from the perspective of instructional theory. In the discourse of instructional theory/educational theory, the relationship between teaching world and other worlds can be discussed from the perspectives of the three worlds, namely the teaching world, life world and science world. Ininstructional theory, the teaching world, which occupies an intermediate position between the life world and science world, can achieve the bidirectional transformation betweenthe life world and science world; in other words, it turns the science world into the life world and transforms the latter into the former. It is in the process of the bidirectional transformation that teaching can achieve its purposes through instilling its influence into students'spiritual world. Therefore the idea of "teaching returning to life" is onesided; instead, it's essential that teaching should focus on the life world, go beyond the life world and toward the science world.