This dissertation sought to understand the evolution of four elementary teachers' (grades 1-3) teaching of science with representations over the course of one year of participation in a multi-structured professional development (PD) project referred to as RepTaL. The notion of learning to teach science using a range of representations is a critical practice of modeling in science (NRC, 2012). Two research questions guided the study: 1) How do the elementary teachers' plans for, enactment of, and reflection on science lessons evolve over the course of their first year in an adaptive PD project? 2) How does the teachers' progress inform the RepTaL team in making decisions about how the PD should evolve? Several pre-collected data sources were analyzed and triangulated including semi-structured interviews, video recordings of teaching, unit plans, and lesson plans. Additionally, retrospective interviews were conducted with two members of the RepTaL team. Employing an interpretative phenomenological analysis (IPA) (Smith et al., 2009) results from this study uncovered three themes from the teachers' practices: a) "an increased focus on students' thinking," b) "explicit instruction on scientific practices," and c) "a shift in representational use from teacher led to student led." The interviews with the coaches revealed they listened closely to the teachers needs and responded to their observations and discussions with the teachers about their practices. This process afforded the PD team the opportunity to "adapt the PD design as needs arose" with respect to both teachers' goals and the RepTaL project's goals. This study provides a detailed look at the advantages of using an adaptive approach to PD, which also includes many of the critical components of PD (Garet et al., 2001). Implications for teacher educators and researchers of teacher education regarding methods of working with teachers and analyzing the process of evolution in their practices are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]