Recruiting students to science and mathematics fields continues to be a nationwide issue, resulting in a dearth of individuals to fill these present and future careers. Novel interventions, especially within the K-12 space, call for a move from content acquisition to the formation of individuals' identity that particularly fosters science and math interest and persistence. Identity research has evidenced results, yet greater communication is needed between the research and practitioner communities to realize the potential of cultivating collective science and mathematics identities in the classroom. In this paper, we bridge these spaces by describing the potential student affordances beyond individual identity formation to that of collective (classroom-level) identity formation considerations by K-12 teachers' within mathematics and science. Specifically, we explore how traditional K-12 classroom structures may reinforce stereotypes and hinder collective mathematics and science identity formation, whereas reform-oriented classroom structures that employ legitimate peripheral participation within a community of practice enable them. Last, we recommend pedagogical interventions to practitioners that promote collective student opportunities to co-construct skills specific to mathematics and science communities as a strategy to foster collective mathematics and science identities. Collective identity formation can provide K-12 classroom teachers pedagogical strategies for additional opportunities or enhanced experiences for students to co-construct and reinforce individual identities in math and science.