“…Given the studies concluding that improvement of number sense skills increases mathematics achievements in years to come (Jordan et al, 2007; Mazzocco & Thompson, 2005; McGuire et al, 2012), lack of instruments that aim to identify number sense skills of primary school students raises concerns. Studies on number sense have been performed with pre‐school students (Aunio et al, 2004, 2006; Howell & Kemp, 2010; Jordan et al, 2007, 2010), primary school students from Grade 1 to Grade 4 (Çekirdekci et al, 2016; Mohamed & Johnny, 2010; Olkun et al, 2015; Yang & Li, 2008; Zanzali & Ghazali, 2002), and elementary school students from Grade 5 to Grade 8 (Akkaya, 2016; Harç, 2010; İymen & Duatepe Paksu, 2015; Kayhan Altay, 2010; Kayhan Altay & Umay, 2013; Lin et al, 2016; Şengül & Gülbağcı Dede, 2013; Torbeyns & Verschaffel, 2016; Yang et al, 2008; Yapıcı, 2013), and preservice teachers (Gülbağcı Dede, 2015; Şengül, 2013; Şenol et al, 2015; Yaman,2015a, 2015b). Among these studies, there are limited number of research works about measuring number sense skills and test development, especially in primary schools.…”