Teachers’ certificates shall be of two classes: First class; and Second class. Each teacher’s certificate issued by the State Superintendent shall be second class when issued. Each county superintendent shall classify the certificate of each teacher employed by the school system of the superintendent’s county at least once every 2 years. In determining the class of the certificate of a teacher, the county superintendent shall consider: Scholarship; Executive ability; Personality; and Teaching efficiency. Each county superintendent shall keep a record of the kind, grade, and class of certificate held by each teacher employed by the school system of the superintendent’s county.