K-12
From School Computing
K-12 (Pronounced "Kay through twelve" or just "Kay twelve") is the North American designation for primary and secondary education.
The expression is a shortening of Kindergarten (5 or 6-year-old) through 12th grade (generally 17 or 18-year-old), the first and last grades of free education in the United States and English Canada.
Some schools are K-12, being that the school gives education from Kindergarten level to the 12th grade.
