66 (o) (1) Basic education structure. The elementary level shall follow the basic national structure and shall provide basic education, the secondary level will correspond to four (4) years of high school, and the tertiary level shall be one year to three (3) years for non-degree courses and four (4) to eight (8) years for degree courses, as the case may be, in accordance with existing laws. (2) Social studies subjects contents. Filipino and Islamic values shall be incorporated in the social studies subjects or their equivalent in appropriate grade levels and subject to agreed norms, academic freedom, and legal limitations. These values shall be taught also as a part of appropriate subjects in the secondary and tertiary levels of education. (3) Textbook preparation, writing, revision and printing. The preparation, writing, revision, and printing of textbooks for the use of the schools in the autonomous region shall be the joint responsibility of the Regional Government and the central government or national government. Subject to agreed norms, academic freedom, and relevant legal limits, the preparation, writing, revision, and printing of the textbooks shall emphasize Filipino and Islamic values. The said values shall include those of Muslims, Christians, and indigenous peoples, human rights, modern sciences and technology, as well as, the latest advances in education that are relevant to the ideals of the autonomous region and to the Republic. (4) Accreditation for transfer to other schools. After they shall have passed the core curriculum prescribed by the central government or national government, the students and graduates of the education system of the autonomous region shall be fully accredited for transfer to the corresponding grade levels in the schools outside the autonomous region. (5) Period for integration of Islamic values. The integration of Islamic values in the curriculum of the regional educational subsystem shall be done over a period of six (6) years from the approval of this Organic Act after appropriate researches and studies shall have been conducted, evaluated, and approved by the regional education authorities.