K 12, full name from kindergarten to 12 grade. Mainly adopted by the United States, Canada and other North American countries, it refers to kindergarten (generally 5-6 years old) to grade 12 (12, generally 17- 18 years old), which is the first two grades of free education in the United States, Australia, Britain and Canada. Therefore, K 12 is also regarded as the general term of basic education stage in the world.

Since kindergarten education in China is not included in the category of compulsory education, K 12 is more synonymous with "primary and secondary schools" in the industry. However, in recent years, with the rise of early education (before entering the park) and preschool education (kindergarten), parents' investment in children's education is not much less than that of primary and secondary schools. In this way, whether from the perspective of the training market or from the perspective of educational investment decision makers, compared with adult education, preschool education is not essentially different from K 12 education. Considering the continuity of education, preschool (0-6 years old) is the reservoir of primary and secondary schools. Before preschool education was included in compulsory education, compared with primary and secondary schools, it was relatively less controlled by the government or schools, and it was easy to cultivate user stickiness.

Therefore, from the layout of online education in K 12, it is undoubtedly a very clever way to include preschool education in K 12, which can also be seen from the layout of Baby Tree (formerly "Learn and Think"), a maternal and child website with good future investment. In fact, it doesn't matter whether preschool education belongs to K 12. For those who set foot in K 12 online education, whether they can embark on online education for preschool education is the most important. Only the online education of preschool education can get through, then it is not impossible to continue early education. Perhaps one day K 12 will become synonymous with the whole non-adult education.