Hirst Bernhardt, ChristineThis dissertation consists of three studies exploring factors affecting whether, when and how students engage in sensemaking in science disciplines, and the epistemological components of instruction that impact their engagement. Each study is grounded in science education reform efforts, including the Next Generation Science Standards (NGSS), which call upon educators to engage students in science practices to learn science through sensemaking and necessitate a reorientation to position learners to “shape the knowledge building work in their classroom community (Miller et al., 2018, p. 1058; NRC, 2012). In other words, students must now act with epistemic agency to figure out more than they learn about (Krist et al., 2019). Study 1 addresses a gap in astronomy education research literature. Astronomy education is largely centered on undergraduates and is minimally researched in pre-college settings. I conducted a qualitative study with thematic analysis of surveys (N = 68) and 10 interviews with select participants to discover methods of teaching and learning astronomy internationally, as a follow on to the quantitative curricular study by Salimpour et al. (2021). I was looking for examples of astronomy as a gateway for further STEM learning in classrooms and community, and as a bridge to equity, as well as examples and takeaways. While the interview participants provided notable examples of programs which disrupt representation gaps in astronomy fields and promote STEM connections amongst historically underserved populations, I did not find easily replicable examples for US teachers to use astronomy as a “gateway” science; I found other nations wrestling with similar issues of deprioritized science instruction, lack of resources and poor access to teacher professional learning opportunities. Therefore, I turned to a deeper understanding of epistemologies of teaching and learning in studies 2 and 3. Papers 2 and 3 investigate the role of epistemological framing, or how people make sense of a particular situation, through speech and behaviors, from past experience (Elby & Hammer, 2010; Goffman, 1974; Hammer et al., 2004). Students may frame learning science as doing school for completion of worksheets and production of “correct” answers for a grade, or they may frame learning science as doing science when they consider “correct” as considering available evidence and weighing it against predicted outcomes to make sense of phenomena or developing disciplinary knowledge through the process of sensemaking (Hutchinson & Hammer, 2010; Miller et al., 2018). In papers 2 and 3, I explored how teachers used framing moves or bids through explicit or implicit signals such as means of instruction, tone, or body language to sustain, shift or redirect students’ approaches to learning activities (Berland & Hammer, 2012). In paper 2, I investigated the impact of two teachers varied framing moves while using similar curricular materials through secondary video analysis. I used codes for cognitive authority and epistemological stance to segment each teacher's dialogue while introducing the activities, or their” public talk,” which established and sustained classroom norms for participation and engagement. I also analyzed dialogue between each teacher and small student groups, as seen from a teacher-worn GoPro camera. I found that one teacher mostly framed the lesson as students doing science and established a culture of collaboration. I found that the other teacher mostly framed the lesson as doing school and established a culture of compliance. However, these findings were nuanced and context dependent. In paper 3, I investigated, through a single case study, how a veteran teacher acknowledged, addressed and adapted her work within the same curriculum from paper 2 to address a mismatch between the epistemic agency afforded by the materials and students’ “typical” epistemic agency enacted in that classroom. I engaged in a collaborative planning interview and observation cycle with the teacher, Amy, over five observations and eight interviews. While I intended to better understand and characterize Amy’s framing moves and how those moves positioned students to act with epistemic agency, I determined that, what I thought were purely her framing moves were also reinforcing embedded commitments (for relationships and community). These commitments were baked into all of her framing moves for sensemaking. I also saw over multiple days that students did not take up her framing bids; after revisiting the data, including a lesson not using the curricular materials, I saw students in her class and school, by structural design, always had some form of epistemic agency, and that the curricular materials suppressed some of the form of epistemic agency to which they were accustomed. By contrast, when Amy modified the lesson to grant students their “typical” epistemic agency, the lesson went well, with students engaging excitedly in scientific argumentation. Therefore, this study demonstrated that the construct of epistemic agency is not monolithic, that the form of epistemic agency matters. Students recognize when there is a mismatch between the epistemic agency invited by curriculum and that which they are accustomed to, which influences their engagement and participation. Amy demonstrated the pedagogical moves and strategies to realign this mismatch.These studies are significant in that many teachers use highly structured materials to assist with NGSS implementation, yet the manner in which teachers approach these materials determine the objectives they establish, and the framing moves they enact, which are likely taken up by students (EdReports, 2022). Paper 3 specifically demonstrates the ability of expert, veteran teachers to understand and act upon knowledge of their students. This knowledge should be leveraged and supported through professional development and curriculum. Paper 1 is also significant because the NGSS embeds and interconnects Earth and Space Science into every grade band in every content area, thus elevating a previously ignored subject matter. Many teachers globally, as Paper 1 demonstrated, are unprepared to integrate this content with efficacy and authenticity. Therefore, we must consider, honor and respect the insight, experience and professionalism of teachers, and work holistically in that space to better understand what they already do well, instead of trying to consistently reshape or re-direct. Perhaps instead of teaching about practices and disciplinary engagement from a deficit stance, professional development should center teachers as professionals to improvise, to experience and to adapt materials as only professionals can. Each of the studies presented in this dissertation describes teachers (or teacher educators in Paper 1) with expert knowledge of their classroom or disciplinary cultures as they relate to engagement, and suggest that we must trust teachers, as professionals, to do just that.  enDissertationScience educationTeacher educationAstronomy EducationEpistemic AgencyEpistemologic Framing