This case study characterizes the inscriptional practices demonstrated by seventh graders, particularly their use of data tables and graphs, in an inquiry-based learning environment. Using a naturalistic approach, we collected multiple sources of data during an 8-month instructional unit that emphasized water quality and relevant concepts. The analyses show that constructing and interpreting graphs and tables provided students with opportunities to discuss, review, and clarify questions about concepts and the inquiry process. At the end of the unit on water quality, students were capable of fully participating in designing a more complicated inscription and interpreting new inscriptions. The findings suggest that four features of the learning environment promoted the development of inscriptional practices: (1) embedding the use of inscriptions in students' science inquiry; (2) providing scaffolds to support students' inquiry process; (3) sequencing tasks and the inquiry process; and (4) engaging students in science inquiry in an iterated manner. This study provides insight into the design of a learning environment in which students can develop competent scientific practices.