“…The results of these research efforts made clear that about 15% to 25% of the differences in students' achievement might be explained by the work of teachers (Aaronson, Barrow, & Sander, 2007;Bosker & Witziers, 1996;Brandsma & Knuver, 1989;Houtveen & Van de Grift, 2007a, 2007bHoutveen, Van de Grift, & Brokamp, 2014;Houtveen, Van de Grift, & Creemers, 2004;Rockoff, 2004;Roeleveld, 2003;Wijnstra, Ouwens, & Béguin, 2003). Students of teachers whose teaching quality is a full standard deviation higher, achieve 10% to 25% more learning gains (Aaronson et al, 2007;Bosker & Witziers, 1996;Brandsma & Knuver, 1989;Hanushek & Rivkin, 2010;Houtveen & Van de Grift, 2007a, 2007bKane & Staiger, 2008;Rivkin, Hanushek, & Kain, 2005;Rockoff, 2004;Roeleveld, 2003;Wijnstra et al, 2003).…”