What topic does the passage mainly discuss?

Education in the United States is usually divided into four levels. These are early childhood, elementary, secondary, and higher education. School attendance is required in every state of the country, and in most states students must attend school until the age of 16.
    The first level is early childhood education. Its main purpose is to prepare children for school. The second level is elementary education. Education at this level is divided into six or eight grades, and children learn Reading, Arithmetic, Writing, Social Studies and Science. They also have Art, Music, and Physical Education.
    The third level is secondary education. It is for junior and senior high school students. Some students take courses to prepare themselves for college. Other students take technical or vocational courses that prepare them for jobs after they graduate from high school.
    Higher education continues after high school. There are many kinds of institutions of higher education. Technical institutes offer two-year programs in electronics, engineering, business and other subjects. After two years at a junior college, students receive an associate degree and then they can continue at a four-year college.