Education in Libya begins with primary education, which is both free and compulsory. Children in Libya between the ages of 6 and 15 attend primary school and then attend secondary school for three additional years (15- to 18-year-olds). About 60 percent of students are assigned to a vocational secondary program, while the remaining 40 percent are assigned to a more academic-focused secondary program, based on test scores and interests. Under Gadaffi, primary and secondary education focused on his treatise on political philosophy, the Green Book, with older students studying "Jamahiriya studies".