This dissertation looks at how responsiveness towards students' science ideas and teachers' understanding of responsive teaching provides opportunities for sensemaking and learning. For this study, I served as the primary science instructional coach for three upper elementary teachers at different schools for at least one school year. We engaged in multiple coaching cycles as part of a larger job-embedded professional development model endorsed by the district and in partnership with a local University. With respect to responsiveness and students' opportunities for sensemaking, I analyzed 30 science lessons where teachers intended to engage students in whole-class sensemaking discussions. I examined how teachers' responsiveness to their students' science ideas worked in combination with other supportive conditions to foster rigorous whole-class discussion episodes. I found that higher rigor episodes were associated with the teacher's use of multiple conditions, often four or more used together. These conditions included combinations of specific talk moves (open-ended questions, follow-up prompts, invitations to others), scaffolds for idea development (pre-discussion tasks, references to activity or representations of activity), and scaffolds for using language to communicate in particular ways (e.g. invoking talk norms; explicit attention to the language demands of a given discussion purpose). With respect to responsiveness and teacher learning, I examined my responsive approach to instructional coaching to identify if or when this approach provided opportunities for teachers' pedagogical experimentation with teaching practices intended to help them become more responsive to their students' science ideas. I define what responsiveness means in a coaching context and propose five dimensions of responsive coaching. There are few examples in the literature that examine the nature of instructional coaching, particularly in one-on-one interactions with teachers. I address this gap by analyzing data from the coaching cycles with three upper elementary teachers to trace the pathways each teacher took in experimenting with these practices. I found that each teacher made productive progress towards fully enacting these practices and all teachers demonstrated an increasing or continued commitment to being responsive to their students' science ideas. In doing so, each teacher and I co-constructed unique learning pathways for each practice---at times, this experimentation gradually advanced their progress, maintained their progress, or stopped-then-restarted their work with a given practice. [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/en-US/products/dissertations/individuals.shtml.]