1 and K 12, educational terms, are abbreviations from pre-school education to high school education, and are now widely used to refer to basic education.

2.K 12 or K- 12, which is the abbreviation of kindergarten Throughwelfthgrade, refers to kindergartens, generally 5-6 years old, to the twelfth grade, generally 17- 18 years old, from the United States, Australia, Britain and Canada respectively.

3.K 12 is mainly adopted by the United States, Canada and other North American countries.