The aim of this article is to study how recent and rapid increase in students' use of smartphones in classrooms affects how participation is organized and carried out in teaching and learning situations, particularly in relation to plenary teaching in whole-class interaction. Smartphones are new artifacts in the classroom that afford changed possibilities for participation in social interaction. This raises questions about to what extent well-established and well-known patterns of classroom participation are still valid, in particular with respect to the fundamental turn-taking organization of plenary teaching. The empirical data consists of video recordings from multiple sources during 158 h of lessons in Swedish and Finnish upper secondary classrooms. Selected interactions involving smartphone use during plenary teaching were transcribed and represented with regard to multimodal aspects of both face-to-face and screenbased interactions. Analysis was carried out using conversation analysis (CA), drawing on the concept participation framework. The main conclusion of the article is that student smartphone use significantly alters participation patterns in whole-class interaction, but in different ways from the students' respective teachers' perspective. However, student phone use is not oriented to as interactionally problematic, or as threatening the basic participation organization of the dominance of IRE-patterns during plenary teaching.