The first author re-entered the middle grades classroom to teach a new National Science Foundation (NSF) physical science curriculum that was designed to foster conceptual change through a scientific approach. The curriculum design met the need and call for reform in science education through its focus on inquiry, evidence-based reasoning, peer collaboration, and deeper understanding of important concepts in a science discipline. Lessons followed a learning cycle of activities for knowledge construction. As a self-study, the first author as teacher sought to learn about his beliefs and abilities in practice while enacting and adjusting the curriculum design. The second author helped in this reflective practice through visiting the first author's classroom for periodic observations, interviews, and discussions about the implementation of this curriculum. Four videotaped lessons and instructional artifacts demonstrate that the teacher enacted the curriculum with high fidelity to its prescribed inquiries and learning cycle format with only minor changes. Instructional design modifications were made in practice to assist lower achieving students meet its high academic challenge of analytical thinking. The merits of the prescribed curriculum for promoting deductive scientific thinking are detailed alongside instructional design decisions emanating from the curriculums' academic rigor and limitations in connecting to adolescent interest and choice. This case details one example of a teacher who intended to faithfully implement.