Introduction

Abstract

Supporting mathematical competence has been identified as an important issue in early childhood education in order to ensure successful participation in knowledge-based societies around the world (Early et al., 2007; OECD, 2018). A growing body of research in recent years has addressed pre- and elementary school children's development of mathematical competence (Linder & Simpson, 2018). This research has highlighted that early mathematical competence is highly important for the development of mathematical competence in later years at school (Duncan et al., 2007; Krajewski & Schneider, 2009; Litkowski, Duncan, Logan, & Purpura, 2020; Nguyen et al., 2016). The development of mathematical competence in children's early years depends on several aspects, ranging from individual characteristics (e.g. children's general cognitive abilities) to environmental ones, such as parents' socioeconomic status or specific learning opportunities provided by the parental home or in institutional early childhood education and care (ECEC) settings (Burghardt, Linberg, Lehrl, & Konrad-Ristau, 2020; Bronfenbrenner & Morris, 2007). Institutional ECEC settings have been identified as relevant learning environments for mathematical competence, in particular (Litkowski et al., 2020; Ulferts & Anders, 2016). However, in order to experience these advantages, ECEC institutions have to offer children high-quality learning opportunities. High-quality learning opportunities in the field of early mathematical learning are characterized by a focus on children's needs and interests as well as on core mathematical ideas in terms of content (Clements & Sarama, 2016; Gasteiger & Benz, 2018; van Oers, 2010). The quality of such learning opportunities depends to a great extent on ECEC teachers' professional competence. Research has shown that domain-specific aspects, for example with respect to mathematics (McCray, 2008), play a crucial role in addition to general aspects of teachers' professional competence (Parks & Wager, 2015). Domain-specific aspects include, for example, knowledge about children's domain-specific development or domain-specific aspects of learning support. ECEC teachers' professional competence in mathematics has been the subject of a growing body of research in recent years. However, there is still a lack of systematic 2literature in this field (Linder & Simpson, 2018). Specifically, no comprehensive overview of descriptions, development and effects of ECEC teachers' competence in mathematics currently exists. This edited volume serves as a first step to closing this literature gap.