Can a school shorten its instructional day by the amount of time that is in excess of the daily minimum instructional time requirements?

Yes. Once daily instructional time requirements are met (5 hours grades 1-6 / 6 hours grades 7-12, it is a local decision as to how the remaining time is utilized.  It has been common for school districts that exceed minimum time requirements to occasionally schedule early dismissals or late arrivals during this excess amount of time for staff development activities or parent-teacher conferences.

For example, when a school’s normally scheduled day exceeds state minimum time requirements by 50 minutes, the school may choose to dismiss classes 50 minutes early each Wednesday. Those 50 minutes provide time for weekly staff development activities.

These planned early dismissals must be cancelled on days when inclement weather requires a delayed start to the day in order that students receive the state required instructional time.