Until the book mentioned in the preceding paragraph is compiled, teaching in matters not enumerated in the first paragraph of the present article shall be in the form prescribed by the superior civil governor. Of the schools Art. 8. In every village, if its population shall permit, there shall be a school for boys and another for girls. [39] Those villages which have a population of 5,000, shall have two schools for boys and two others for girls. Those which have a population of 10,000, shall have three schools, and so on, increasing at the rate of one school for each sex for every 5,000 inhabitants, whenever an average of more than 150 children shall have attended all the existing schools during the last three months. [40] In the visitas, very distant from the villages, whose population reaches 500 inhabitants, there shall also be a school for each sex, and if there is more than one visita, and together they have that number of souls, the schools shall be established in the most central. If the number of children of one school exceeds eighty there shall be one assistant, and if it exceeds one hundred and fifty, two. Art. 9. Schools shall be located in the most central part of the villages or barrios, and must be built well lighted and ventilated, with dwelling rooms for the teacher and his family; but such dwelling shall be independent [of the school] and have a special entrance. [41] Art. 10. The schools shall conform to the classes fixed by article 5 of the royal decree of this date. Of the teachers Art. 11. The rank of teacher in the public schools of primary instruction belongs to the pupils of the normal school who are qualified with the suitable certificate, who shall be fully twenty years old, and possess the other requirements expressed in article 20. Art. 12. Teachers shall enter the schools of entrada or ascenso, in accordance with the right which their respective certificates give them, according to the terms of article 7, of the regulations of the normal school for male teachers, approved by her Majesty on this date. After three years of teaching, the teachers may be promoted to the next class, whether of ascenso or término of the second class. When two or more teachers aspire to schools of higher rank, if their respective certificates are equal, he who has taught longer shall be preferred. If the certificates are not equal, he who possesses a certificate for a school of ascenso shall be preferred to him who has one for a school of entrada. Art. 13. In case of the absolute lack of candidates with the necessary certificate, those who hold lower certificates may be appointed teachers for a school of the upper class, but it shall be ad interim, and they shall receive the pay belonging to the class of their certificate, until they complete the time of exercise with good mark, in which case they shall be appointed regularly.