This article focuses on research carried out in a private school in Bogotá with a group of English as a foreign language fourth-graders. The study aimed to analyze interaction in the English classroom through action research, based on tasks that promoted collaborative work and involvement of the students and their teacher. The instruments to collect data were video recordings and artefacts from the students' tasks in the classroom. The analysis of classroom interaction involved the steps of conversational analysis stated by Seedhouse (2004). The study allowed the description of unexpected patterns of interactions among students and their teacher, which revealed changes in the classroom dynamic as a result of the action research plan.