(a) Upon rating a teacher or a principal as developing or ineffective through an annual professional performance review conducted pursuant to Education Law section 3012-d and this Subpart, a district shall formulate and commence implementation of a teacher or principal improvement plan for such teacher or principal by October 1st in the school year following the school year for which such teacher’s or principal’s performance is being measured or as soon as practicable thereafter.

(b) Such improvement plan shall be developed by the superintendent or his or her designee in the exercise of their pedagogical judgment, and subject to collective bargaining to the extent required under article 14 of the Civil Service Law, and shall include, but need not be limited to, identification of needed areas of improvement, a timeline for achieving improvement, the manner in which the improvement will be assessed, and, where appropriate, differentiated activities to support a teacher's or principal's improvement in those areas.