Educational reforms have a tendency to fade or divert in unproductive ways. To disrupt this cycle and understand why unwanted practices persist and new ones distort, the supports that sustain practices need to be considered. In this study, I use action research to examine the supports of institutionalized patterns of practice within the classroom and at other levels, illuminating the interconnected web of influence that shape classroom practice. I leverage the analytical power of the MoRe Institutional Framework (Anderson & Colyvas, 2021) to investigate support mechanisms. I present a descriptive case study of practices and supports of an interdisciplinary science course for undergraduate elementary education majors. I explore supports for classroom practices of representing science and centering of students and/or teachers. My findings show patterns of practice supported in multiple ways at levels from individual to global. Implications of this study suggest ways for changing classroom practice and show how the application of the MoRe Institutional Framework to classroom systems could further inform and service reform efforts. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]