Complex sentence: Dance, band, and choir are rehearsed during the school day and there are three opportunities for students' work to be displayed throughout the year, at the midpoint and end of the fall semester, and at the end of the spring semester.
Split into simpler sentences: Dance, band, and choir are rehearsed during the school day and there are three opportunities for the students' work to be displayed throughout the year. Once at the midpoint of the fall semester, again at the end, and once at the end of the spring semester.