“…On the contrary, researchers seem to associate school effectiveness with various factors such as improving students' achievements (Houtveen et al, 2004), improving the quality of instruction (Thoonen, 2012), redressing social inequality (Thrupp, 1995;Sammons, 2007), preparing students for the job market, and increasing productivity (Heyneman, 1997). 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).…”