Teaching science for understanding rests on continual use of overlapping forms of formative assessment, supported by scaffolding and highly interactive and responsive learning experiences for students. In this study, the authors use a sensemaking perspective to understand the complicated work of one middle-school teacher team grappling with multiple accountability and improvement initiatives and a jumble of pedagogical frameworks. The authors describe how this team used promising practices for meaningful data use when teaching science for understanding. Specifically, the data themselves were more meaningful to the teachers, the team had constructed meaningful routines for using data to make inferences about student learning and conjectures about instructional adaptations, and the use of student data was integrated into a larger framework for science teaching, oriented toward deepening students’ understanding of science. Although atypical, this case study illustrates that meaningful data use by a team of teachers can anchor thoughtful science teaching that is attentive and responsive to students’ unfolding science ideas.