The present study is interested in how oral expression is managed in classroom interaction and aims to contribute to our understanding of how personal opinion is sequentially organized in this context and what institutional practices are used by the teachers in order to lead students to reconfigure the way they proffer it during open discussion activities. Through a single case analysis and using Conversational Analysis, we analyze in detail a prototypic question-response sequence that regularly occurs in personal opinion exchange activities in our data. Based on a corpus of 7,5 hours of interaction that was audio and video recorded in French L1 classrooms of Western Switzerland, the data come from a degree of obligatory schooling referred to as secondary-1 and involve students aged between 13 and 14 years old. The expression of personal opinions holds our interest because this everyday activity is not explicitly evaluated in the classroom and yet, it is particularly challenging for students. Although students have at their disposal the linguistic resources to express their opinion, the interest lies in the way the teacher and the students adjust their interactional practices in order to display to each other the appropriateness of a given conduct.