The school boards of all school districts may establish salary schedules based on training, experience and other such factors as may be incorporated therein, including student progress and performance as developed by the State Board of Education, paying teachers greater amounts than the scale provided herein, but no teacher may be paid less than the amount based upon the minimum scale of pay provided in the adequate education program as prescribed in Section 37-19-7, Mississippi Code of 1972, and all supplements paid from local funds shall be based upon the salary schedules so established. The school boards may call upon the State Department of Education for aid and assistance in formulating and establishing such salary schedules, and it shall be the duty of the State Department of Education, when so called upon, to render such aid and assistance. The amount actually paid to each teacher shall be based upon and determined by the type of certificate held by such teacher.