A. Each public school governing authority shall use the following ten-point grading scale for students enrolled in any grade for which letter grades are used:
(1) One hundred points through ninety points is an A.
(2) Eighty-nine points through eighty points is a B.
(3) Seventy-nine points through seventy points is a C.
(4) Sixty-nine points through sixty points is a D.
(5) Fifty-nine points through zero points is an F.
B. The provisions of Subsection A of this Section do not apply to any school that is operated by the United States Department of Defense and that is located on a federal military installation.