(a) A junior high school shall consist of the seventh, eighth and ninth grades, organized as a separate unit with approved courses of study and approved apparatus and library.

(b) A middle high school shall maintain an approved course of study covering one year of high school work above the eighth grade. It shall have approved apparatus and library.

(c) A high school (senior) shall maintain an approved four-year course of study above the eighth grade and shall have approved apparatus and library. Such term shall include the six-year high school, covering the work of grades 7 to 12.

(d) Industrial high schools may offer one-, two-, three- or four-year industrial or trade courses open to pupils who have completed the work of the eighth grade of the elementary schools. Such schools shall be organized as a separate unit with distinctive, approved courses of study and with approved equipment and facilities for industrial and trade education.

(e) Technical high schools may offer three- or four-year general or specialized technical courses of secondary school grade. Such schools shall be organized as a separate unit with distinctive, approved courses of study and approved equipment for technical work.

(f) Continuation high schools may offer general or specialized courses open to pupils 16 and 17 years of age who are not regularly enrolled in the full-time schools. Such schools shall be organized as a separate unit with distinctive courses of study and equipment and facilities adequate for providing the proper instruction for working children.