Complex sentence: The add-on was built on top of the football field, has two floors, has a new cafeteria, has a new sports equipment storage area, contains all the 6th grade classrooms, and most of the 7th grade classrooms.
Split into simpler sentences: The add-on was built on top of the football field. It has two floors, has a new cafeteria, has a new sports equipment storage area, contains all the 6th grade classrooms, and most of the 7th grade classrooms.