To develop critical reasoning skills potentially advances students' ability to critically consume information, make informed decisions, and actively participate in a democracy. An inquiry-based pedagogical approach to science teaching remains an effective means to develop critical reasoning skills. Participating in scientific inquiry requires students to generate arguments and test alternative hypotheses using experimental evidence. Scientific inquiry demands that students use their critical reasoning skills. Unfortunately, many teachers fail to allocate an adequate amount of time for genuine experimentation in science classes. As a result, science classes often leave students unprepared to think critically and apply their knowledge in a practical manner.

The focus of this study was to investigate the extent to which an inquiry-based professional development experience, including a two-day summer workshop and 18 weeks of follow up Professional Learning Community (PLC) support, affected the attitudes and pedagogical skills regarding scientific inquiry among six high school biology teachers. A concurrent mixed methods, action research design was used to measure changes in teachers' attitudes, perceptions, and skills regarding inquiry-based pedagogy was measured throughout the 22 weeks of the study. A survey instrument, card sorting activity, classroom observations using the Reformed Teacher Observation Protocol (RTOP), individual interviews, and PLC observations were used to gather data. Results indicated the professional development was effective in transforming the participating teachers' attitudes, perceptions, and skills regarding inquiry-based pedagogy.