Teacher preparation programs commonly use observational instruments to assess the progress and the exit performances of teacher candidates. However, while these instruments have been described and several have been studied for effectiveness, the field lacks a close examination of how they position participants: teacher candidates, K-12 pupils, and teacher educators. This article closely examines three classroom observation instruments used in preservice programs. We use critical discourse analysis (CDA) and systemic-functional linguistics to examine how the grammar of these instruments assigns agency and positions participants as teachers and learners, and define their larger discourses of professionalism and accountability. We argue that instruments differ in the extent to which they grant participants agency, thus influencing the assumed pedagogical relations among the teacher educator, teacher candidate, and K-12 pupils. Instruments are not neutral, but reflect the values of the programs that use them, inflected by often contradictory discourses of teacher and student learning.