As part of a broader study of the impact of teaching environment and preparation on the conceptions of teaching and learning expressed by our graduate Teaching Assistants (TAs) and undergraduate Learning Assistants (LAs), we track shifts in instructor awareness of student ideas over the course of a week of preparing for and teaching in the Tutorials in Introductory Physics. Since TAs and LAs interact face-to-face with introductory physics students, we are interested in the nature of their educational practice and its impact on the success of reformed teaching methods. In this study, we focus on a specific component of educational practice by asking recitation instructors to describe student difficulties with topics at various points in a week of teaching. We observe increased awareness of student difficulties on the Tutorials following preparation, but also conclude that resources like the Tutorial pre-test are not necessarily alerting TAs and LAs to the ideas they should be prepared to discuss with their students.