Science education literature calls for students' participation in science practices through ongoing collective sensemaking built on coherence from the student perspective. However, few studies systematically consider students' point of view and there is little guidance for how teachers can lead the class to co-construct specified learning goals while simultaneously expanding what counts as science and centering students' ideas, even when they diverge from the curriculum's intended plans. In response, this dissertation examines how elementary teachers and students use lessons designed to support coherence from the student perspective, and how they diverge from those plans, in order to engage in scientific sensemaking. First, I observed and analyzed three different classrooms and their designed curricula to explore how connections between lessons within a unit are incorporated into curricular materials, planned for by teachers, and enacted by the class community. Comparison across these phases and between the three classrooms revealed ways that coherence in planning and teaching influences students' perceptions of coherence, and, as a result, their participation in sensemaking. Second, during one teacher's unit that intentionally positioned students as epistemic agents, I analyzed the public instances when student ideas diverged from the written curriculum and teacher's expectations for the unit. The students' ideas and the responses they received influenced students' collective sensemaking and their roles in it. [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.]