The state board of education shall adopt rules to facilitate job-sharing positions for classroom teachers, as the term "job-sharing" is defined in this section. These rules shall provide that a classroom teacher in a job-sharing position shall receive paid legal holidays, annual vacation leave, sick leave, and personal leave on a pro rata basis. "Job-sharing position" shall mean any position:
(1) Shared with one other employee;
(2) Requiring employment of at least seventeen hours per week but not more than twenty hours per week on a regular basis; and
(3) Requiring at least seventy percent of all time spent in classroom instruction as determined by the employer;