As used in this chapter, "school year" means the annual period commencing on the first day of September of one calendar year and ending the last day of August of the ensuing calendar year: Provided, That for those school districts or charter schools commencing basic education program prior to September 1, the following activities shall be considered to be within the school year that commences September 1.

(1) School days scheduled prior to September 1; and

(2) Staff days and activities in preparation for the school year included in employee contracts for the school year, but occurring before September 1.