The length of secondary school study in the United States has always been different from state to state, but since the emergence of public secondary schools, it has generally been four years, which constitutes the 84-year academic system of general education in the United States (that is, eight years in primary school and four years in secondary school). 1888, Eliot, president of Harvard University, criticized the 1984 academic system for the first time. After discussion from all walks of life and argumentation by educators, the 633 academic system was formed at the beginning of the 20th century. That is, six years of primary school, three years of junior high school and three years of senior high school, so that the last two years of primary school and the first year of middle school are merged into junior high school, and the last three years of middle school are changed into senior high school. In the future, the education system in the United States will be mostly six-three-three, and some States will retain eight-four and implement six-six.