This mixed-methods study explored the pedagogical practices of Prospective Elementary Mathematics Specialists (PEMSs) as they completed a university K-5 Mathematics Endorsement program. Participants were 13 elementary teachers at an urban, high-needs charter school. Data were collected via individual interviews, written reflections on enacted teaching practices, two observations of classroom teaching practices, and a 36-item Cognitively Guided Instruction Teacher Knowledge Assessment. The findings show the PEMSs were connecting their learning during program courses with instructional practices in their classrooms, as 85% were implementing standards-based learning environments (SBLEs) at a high level, with the classroom event of providing their students opportunities to make conjectures about mathematical ideas as a relative struggle. The PEMSs described pedagogical shifts across the program, providing insights into these changes, along with how particular program components contributed, with the emergent themes of "skepticism," "trying it on," "shifters," and "need more support."