This article critically reviews Leslie P. Steffe’s work Children’s Mathematics and Mathematics of Children by focusing on the ontological and epistemological dimensions of children’s mathematics from a constructivist perspective. The study employs a library research approach combined with philosophical analysis of Steffe’s central ideas concerning the nature of mathematics, the construction of children’s mathematical knowledge, and the methodology of teaching experiments. The findings indicate that Steffe conceives mathematics not as an objective entity existing independently of human beings, but rather as a product of human intellectual activity that develops through mental operations and social interaction. Within this framework, Steffe distinguishes between children’s mathematics as the mathematics constructed by children and mathematics of children as the conceptual model developed by researchers to explain children’s mathematical activity. Furthermore, this article demonstrates that the teaching experiment approach developed by Steffe represents a constructivist methodology integrating teaching and research in order to understand the development of children’s mathematical thinking in depth. The study also reveals that Steffe’s thought has significant implications for curriculum, instruction, assessment, teacher education, and contemporary mathematics education research, particularly in the development of meaningful, reflective, and student-centered learning. Nevertheless, Steffe’s perspective also presents certain limitations, especially due to its predominant focus on individual construction, which leaves the social and cultural dimensions of mathematics insufficiently elaborated. Overall, Leslie P. Steffe’s work provides an important contribution to the reconstruction of modern philosophy of mathematics education by positioning children’s mathematics as a legitimate cognitive reality that deserves to serve as a foundation for the development of mathematics education.
Keywords: constructivism, children’s mathematics, epistemology of mathematics, ontology of mathematics, teaching experiment, Leslie P. Steffe.
