Cultural and historical reasons have led to a highly decentralized and diversified education system in the American Republic. There are no federal or national institutions save for the military academies, and within most states control of local school districts is devolved to a locally elected school board of non-professionals. Thus, the exact methods, curricula, standards, and practices in education vary from district to district and from state to state. Elementary and secondary education is funded by state or local governments and free to the student; slightly more than 11% of the national student population is enrolled in private education, which range from independent boarding schools to parochial schools operated by Catholic dioceses and orders to schools operated by for-profit consortia. A growing number of students are also home-schooled by their families or private tutors. In most states, education begins at age 5, when children are enrolled in kindergarten. Kindergarten is followed by first grade and then four or five more years of elementary school. After elementary education, students enroll in so-called middle school or junior high school, which encompasses grades 6-8, 7-8, or 7-9 depending on the local practice. High school, i.e. senior high school follows for grades 9-12 or 10-12 depending on the local practice. The high school years are also referred to as freshman, sophomore, junior, and senior years. Starting in 2002, students are required to take periodic standardized achievement tests to be used to rate their performance and that of their schools and districts. K-12 education reformers have succeeded in different areas at creating charter schools, which release a school from certain regulations under a contract to exceed performance; magnet schools, which draw students from a wide area to focus on a particular subject; and school choice programs, in which parents are permitted to select the school their child will attend. During the eleventh or twelfth grades, students intending to pursue higher education apply to postsecondary institutions and take a battery of national examinations known by their initials, such as PSAT/NMSQT, SAT/SAT II, ACT, ASVAB, ELPT, AP, CLEP, and IB. For those who do not, education is typically compulsory between the ages of 6 or 7 and 16. Those without a high school diploma can complete a course known as the GED as adults, which is considered equivalent. Most students continue to post-secondary education, generally referred to as college (i.e. the stage of education, regardless of whether the institution is named a "college," "university," or "institute"). All states sponsor subsidized universities or specialized college systems, and there exist a substantial number of private institutions. The federal government sponsors a number of financial aid programs for higher education in the form of loans, grants, work-study, community service grant, and military service grant programs. In the case of a junior college or community college, the student enrolls in a two-year proram resulting in an associate's degree, usually resulting in certification in a career field. Larger colleges and universities grant bachelor's degrees (e.g. A.B., B.S.) after a 4-year program, although some specialized degrees (e.g. B.Arch, B.F.A.) are stipulated to be 5-year programs. Post-graduate education for masters, doctorate, or professional degrees such as the M.D., J.D., or Ph.D. is supported by the university systems and in some cases by specialized institutions. Continuing education programs are sponsored by many institutions, and cooperative extension programs are required of "land grant" and "sea grant" universities which received land or funding from the federal government at their founding. The U.S. claims a literacy rate exceeding 97%.