Non-contact time (non-teaching and/or non-supervisory) for full-time classroom teachers shall be at least two hundred and sixteen (216) minutes per cycle, exclusive of recess. A part-time teacher is entitled to a prorated share of non-contact time. This minimum time is subject to variation with the agreement of the teacher or where, due to urgent circumstances which were unforeseen when school timetables were established, the Division is required to provide less non-contact time on a temporary basis.