Substitute teaching is by its nature inherently indefinite depending as it does on the occurrence of unforeseen vacancies in the teaching faculty; however, the employment possibilities of a substitute teacher remains reasonably assured so long as the claimant intends to do the work and the district expects to offer the work as it becomes available.Guth v. Unemployment Compensation Board of Review, 81 Pa.Cmwlth. 79, 473 A.2d 228, 231 (1984). The legislature and the agency have treated school district employees differently than other employees. Unemployment benefits are not paid to teachers during the period between successive academic years or terms. Iowa Code ยง 96.4(5)(b).