Programs that provide underserved populations with access to high-quality mathematics through workshops, clubs, and classroom observations (Civil, Stoehr, & Salazar, 2019; Civil & Bernier, 2006; Diaz-Palomar, Menendez, & Civil, 2011; Jimenez-Castellanos, Ochoa, & Olivos, 2016; Muir, 2011, 2012; Quintos, Civil, & Bratton, 2019) are vital. The community mathematics project (CMP) is one such program that takes a holistic approach to transforming mathematics education. Through partnerships with local institutions, the CMP pairs a prospective teacher (PT) with a parent for online mathematics tutoring sessions. This study describes how PTs in the CMP supported parents' mathematics development of sense-making (Odden & Russ, 2017) in mathematics by providing relevant tasks, employing multiple strategies, using virtual manipulatives, and questioning in one--one-one tutoring sessions. Findings suggest that this type of field experience with an explicit focus on a sense-making approach supported PTs in learning mathematics, engaging in partnerships with parents and members of the community, and attending broader issues of social contexts of learning. Further, PTs attended to individual considerations such as sequencing and scaffolding, relevancy of the content, task development, and building towards common mathematical practices. Finally, onsite coaching and tutoring experiences were formative in developing essential skills for teaching mathematics in elementary school in the following areas: content and pedagogical content knowledge, development of core pedagogical practices, funds of knowledge approaches and collaboration with families, and dispositions toward (teaching) mathematics such as reframing mistakes, emphasis on sense-making, and co-construction of knowledge.