(a) The amount of a grant awarded under the program to a full-time undergraduate student equivalent enrolled at an eligible institution for an academic year may not exceed the lesser of:
(1) the difference between the amount of tuition and required fees charged to the student by the institution for that academic year and the amount of any other gift aid, including state or federal grants or scholarships, awarded to the student for that academic year; or
(2) $500.
(b) The coordinating board may adopt rules that allow the coordinating board to increase or decrease, in proportion to the number of semester credit hours or competency units or credits in which a student is enrolled, the amount of a grant award to a student who is enrolled in a number of semester credit hours or competency units or credits in excess of or below 12 semester credit hours or an equivalent number of competency units or credits.