A single-session kindergarten class shall meet all of the following criteria:
(a) The class is maintained for a minimum of 180 minutes per schoolday.
(b) The kindergarten class teacher is assigned to only one session of kindergarten daily as a principal teacher.
(c) The kindergarten teacher is a full-time certificated employee.
(d) The kindergarten teacher shall be available for assistance or assignment in the instructional program of the primary grades when not involved in the kindergarten program.