“…Accordingly, we cannot reject the null hypotheses that the textbooks do not affect children's learning progress in reading comprehension and engagement in reading. These results are somewhat surprising, given that former research on the effects of textbooks generally found significant effects for academic performance (Goffin et al, 2016;Bellens et al, 2019(e.g., Törnroos, 2005Van Steenbrugge et al, 2013;Hadar, 2017;van den Ham and Heinze, 2018). Furthermore, there are also several theoretical reasons to expect that textbooks matter for student's academic performance (Schmidt et al, 1997;Valverde et al, 2002;Törnroos, 2005) in reading comprehension and engagement.…”