Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
† proschŏlus, i, m., = πρόσχολος, an under-teacher, under-master (post-class.): tam pauper, ut proscholus esset grammatici, Aug. Serm. Apostol. Serm. 178, n. 8; Aus. Prof. 22 in lemm.