“…Several individual factors have been shown to affect the development in general and in mathematics in specific. Some of these are sex (see, e.g., Metsämuuronen 2017a; Niemi et al, 2020Niemi et al, , 2021, and language background including medium of instruction being the mother tongue (first language, L1) or the second language (L2) (see, e.g., Kuukka and Metsämuuronen, 2016). Other important factors found to explain the competence are relative age of starting the school (see, e.g., Dhuey et al, 2019;Kivinen, 2018;Ukkola et al 2020), attitudes toward school and self-efficacy (see, e.g., Aunola, Leskinen, & Nurmi, 2006;Bandura, 2012;Lerkkanen et al, 2010Lerkkanen et al, , 2012Tuohilampi and Hannula, 2013; see in-depth in Ukkola et al, 2020).…”