1. Except as otherwise provided in subsection 2, such part of the expenses of making any public improvement, as the board determines by an affirmative vote of at least two-thirds of its members, may be defrayed by special assessments upon lands and premises located within the district and abutting upon that part of the street or alley so improved or proposed so to be, or the lands located within the district and abutting upon the improvement and the other lands as in the opinion of the board may be specially benefited by the improvement.
2. All property owned and used by a school district is exempt from any assessment made pursuant to the provisions of this chapter.