The study investigates how the discursive practices in a physics class were constrained by social forces associated with the larger context in which teaching and learning were situated. The teacher understood teacing and learning in terms of constructivism, believed that students should have more autonomy in the classroom, and structured activities to involve students actively in the learning process. However, despite his efforts to enact the curriculum in a manner that was consistent with constructivism, the emphasis still was on goals such as learning to use formulas to perform calculations and memorizing facts. In addition to constructivism, belief sets that shaped the enacted curriculum related to time being scarce, content coverage being a primary concern, and students needing to be prepared for examinations. A characteristic of the classroom community was a relative imbalance between the voices of science and common sense. Even though the teacher was concerned with students making sense of physics, examples are provided of students accepting the viability of scientific claims despite contradictions with their common sense notions.