Background: In the field of science education, adults often set up practical-based activities with the idea of stimulating children's reasoning and approaching science in a playful way. Although the potential role of objects in stimulating social practices has been considered in the literature, how teachers work on semiotic aspects of argumentation is still less explored. Purpose: In this paper, the purpose is to identify how practice-based experiences settled up by teachers shape children's argumentation in science education. Sample design and methods: We analyzed argumentation in science tasks involving a total of 39 children (6-7 years old) and their three teachers, coming from two different classrooms of cycle 1 (Harmos, grades 3-4) recruited in the French speaking-part of Switzerland. The tasks were video-recorded and then transcribed. Through the lenses of the pragma-dialectical approach, we selected the argumentative discussions emerging during the experiences and we performed a qualitative analysis of these interactions, by looking at different semiotic resources: speech, gaze direction, deictic gestures, and position of physical objects. Results: The findings show that teachers play a crucial role in sustaining children's argumentation by the integration of different semiotic resources during the activities. Conclusion: As argumentation in classroom evolves through the mobilization of various communicative tools, the present study can contribute to strengthen the interplay between different channels of interaction during science education at primary school.