Purpose: The purpose of this paper is to highlight the ways racialization in K-12 mathematics classrooms has narrowed the understanding of mathematical learning for Black children. Design/methodology/approach: Drawing on situated learning theory and funds of knowledge, the authors argue that the social learning context of mathematics classrooms has limited the understanding of what Black children are capable of mathematically. The authors suggest that as a community of practice, mathematics classrooms may be marginalizing Black children, as well as other students of color, by devaluing their community-based knowledge and ways of knowing. Findings: The extant literature portrays Black children as struggling in mathematics; however, this research is overwhelmingly conducted based on school performance measures. Yet, if one looks beyond the classroom to Black children's homes and communities, a plethora of mathematical knowledge tied to cultural and community practices may be found. As such, Black children who struggle in mathematics classroom may be experiencing misalignment across contexts, rather than a lack of mathematical knowledge altogether. Practical implications: This paper has implications for classroom practice, particularly teacher ideologies pertaining to community-based knowledge. The authors urge mathematics education researchers and practitioners to look beyond the classroom, as community-based mathematical practices may provide more insight into students' mathematical capabilities. These implications are particularly important for educating students of color, who often experience a subpar classroom education. Originality/value: In this paper, the authors provide a critical lens to situated learning theory, pushing mathematics education research to examine the underexplored topic of Black children's out-of-school mathematical practices.