We used a mixed-methods study to understand the nature of classroom instruction and the enactments of inquiry with nine teachers after an extensive professional development (PD). The "Summer Ecology Institute for Teachers" focused on science as a process and included mentoring by scientists and science educators. We validated our findings using a triangulation approach with multiple data sources: pre-post attitude surveys, classroom observations using the CETP-COP protocol with observation notes at 5 minute intervals, semi-structured interviews, and review of student science notebooks. Our first three findings address the nature of classroom instruction:1) in their classroom practice the nature of the instruction was as mentors for K-12 students as they engaged in scientific inquiry, 2) the teachers' instructional practices were drawn from their own emerging identities as scientists who practice scientific inquiry in their interactions with their K-12 students (TIS) and 3) the classroom practice of the teachers promoted high levels of cognition and student engagement. A fourth finding addresses the enactment of inquiry in teachers' classrooms: Finding 4) while teachers integrated inquiry into many aspects of their classroom instructional practices, there was unevenness in the components of the inquiry enactments. Implications for PD are included.