ABSTRACT The Earth Core program provided earth science content to urban public school sixth grade teachers who lacked geoscience training during a one-week workshop with the goal of increasing participants' pedagogical content knowledge (PCK) and confidence in teaching earth science. The workshop evolved from a concern that teachers would not have the training or experience required to engage students with earth science material due to new state standards switching geoscience instruction from 8th to 6th grade. The program, aligned to Cochran's (1992) five suggestions for enhancing teachers' PCK, was set up to encourage participants to reflect by sharing teaching ideas, to discuss what we found to be often naïve earth science conceptions, share lesson plan ideas, and conduct action research. Field trips facilitated a bonding experience that encouraged collaboration of participants, and interactive lesson activities helped participants recognize their limited knowledge of earth science. Both qualitative and quantitative data collection methods were used in a mixed methods approach to this study. Participant confidence in teaching earth science was slightly elevated after the workshop. The study suggests that teachers realized how little earth science understanding they have after being confronted with advanced level geoscience concepts. INTRODUCTION A worthy goal for professional development is to enhance teacher's pedagogical content knowledge (PCK). PCK was first introduced by Shulman, 1986; Shulman, 1987; van Driel et. Al., 1998, as a theoretical framework, for understanding the knowledge base necessary to teach. The key elements of PCK include knowledge of the subject material, and understanding of student misconceptions about the content. While most research has focused on how PCK influences the teaching process, little research involves enhancing PCK during in-service programs. Loucks-Horsley, et al., 1998; Loucks-Horsley, et al., 2003; Schuster and Carlsen, 2006, suggest that staff developers with an understanding of adult learning literature ineffectively communicate educational concepts to the content specialists conducting professional development workshops. The Earth Core program relied on content specialists and adult science education developers co-teach a professional development workshop using Cochran's (1992) four suggestions for teachers to enhance PCK. These recommendations encourage teachers to be more reflective about why specific ideas are taught the way they are, explore in new ways how students think about the concepts being taught, exchange ideas with other teachers about teaching difficult concepts, and conduct action research. The program also aligned to the National Research Council (NRC) science education professional development standards (NRC, 1996), which focus on learning science content through inquiry, integrating science content knowledge with pedagogical knowledge, developing a capacity for lifelong learning, and integrating program components to aspects of school life. Additionally, the National Science Education Standards promote more emphasis on inquiry teaching and learning, integration of theory and practice in school settings, teacher as intellectual, reflective practitioner, teacher as leader, and teacher as a member of a collegial professional community (NRC, 1996; Yager, 2005). DEVELOPMENT AND CONTEXT OF EARTH CORE This study was conducted in a large urban system in Georgia, in response to a change in State standards. In 2005, State education standards moved the earth science curriculum from eighth to sixth grade. This change had two significant consequences on the students and teachers. First, students in this southeastern state no longer take a geoscience specific course after 6th grade. Unless students are engaged in the material, it is possible they won't pursue earth science as an elective in high school, or in college. The U.S.is currently at a critical junction in earth science- only 4.6% of all BS degrees in geosience are awarded to African- American and Hispanic students (Strategy for Developing a Program for Opportunities for Enhancing Diversity in the Geosciences, 2006). Therefore, to maintain an essential pipeline of geoscience majors in the post- secondary stream, the curriculum must be engaging in their sole required encounter in the K-12 system. Second, although the standards changed, the teaching staff did not: sixth grade science teachers who formerly focused on life and physical science would now be teaching earth science, with no formal geoscience training. Although Earth science will be taught for two years in both eighth and sixth grades, after this time, sixth grade life science teachers will be the sole contact students have with earth science. To address these issues, we developed a professional development program for these 6th grade teachers named Earth Core, with funding from the National Science Foundation (NSF) - funded Partnership for reform in Science and Mathematics (PRISM) Earth Core: Enhancing Delivery of Geoscience Content in a Diverse School System During Times of Changing State Standards John L. Pecore Georgia State University, College of Education, MSIT, Atlanta, GA 30302-3978, JLPScience@aol.com Beth A Christensen Adelphi University, Environmental Studies Program, Science 103, Garden City, NY 11530, Christensen@adelphi.edu Heather Mobley Qualitative Research Consultant, 500 Lanier Ave West #203, Fayetteville, GA 30214, hmobley@groupaccessinc.com Nydia R Hanna Georgia State University, College of Education, MSIT, Atlanta, GA 30302-3978, NydiaH@mac.com