This research is embedded in the context of tertiary education in Vietnam where the instruction giving stage is assessed. Drawing on a Conversation Analysis perspective, the study aims to reveal teachers' instructional patterns in three EFL classes of freshmen, thus not only maximizing the interactional structures that can enhance classroom communication but also minimizing the problems that can hinder teacher-student exchange. The findings show that two main instructional styles that can be classified from the inspected discourse namely, interactive instruction containing students' contribution and monologue-type instruction with little learners' involvement. Positive and negative aspects implied from the instruction giving phase that impact on classroom language are also enumerated prior to suggesting implications for educators to implement.