“…Despite the diversity of opinions, though, what they do seem to agree upon (see e.g., Kalin and Zuljan, 2007;Reynolds, 2010;Saitis and Saiti, 2018) is that, in order for schools to be considered effective, they should (among other things) demonstrate competent leadership, regularly updated curricula and textbooks, adequate teaching means, proper material and technical infrastructure, unobstructed administrational operation as well as close cooperation with parents (Thoonen, 2012;Babalis and Tsoli, 2017). What they particularly need, though, is scientifically and pedagogically trained teaching staff with adequate and updated knowledge/skills and a positive attitude with regard to teaching, learning, and classroom management aspects (Flower et al, 2017;Révai and Guerriero, 2017). Indeed, it is common knowledge in modern management theory-both within and outside the educational field-that in order for an organization such as a school unit to operate effectively, material resources per se are not sufficient and cannot yield results without the contribution of staff members (Gamage and Pank, 2003).…”