The purpose of the current study was to: (a) examine the frequency of prior knowledge (PK) activation in elementary classrooms while students were engaged with text, (b) investigate the relevance of students' responses to teacher prompts, (c) explore the nature of teachers' and students' prior knowledge activation utterances, and (d) investigate whether there were discernible routines in the interactions between teachers and students when activating PK. Participants were 6 teachers and 99 students from a private elementary school in the mid-Atlantic. An analysis of classroom discourse suggested that teachers infrequently prompted students to activate their prior knowledge during reading. Yet, when teachers did prompt PK, they asked about a prior lesson most often, or about a specific text, students' world knowledge, or their personal experiences. Students then responded to their teachers according to the prompted referential frame. Additionally, four routines of classroom discourse were identified in the data including "nonresponsive," "question-answer," "simple feedback," and "interaction" routines, with less elaborate routines being most common and primarily occurring at the beginning of lessons.