Live oral exchange via videoconferencing is known to offer useful affordances for English as a foreign language (EFL) learning: the development of communicative abilities increases collaboration skills and motivation to learn English (Botturi et al., 2018; Okumura, 2020). Techno-pedagogical factors shown to be conducive to productive L2 exchanges with young learners include careful sequencing of learning activities, short task-based sessions with small groups, and pedagogical support for teachers in their own classroom context (Whyte & Cutrim Schmid, 2018). There may, however, be a significant gap between these recommendations and the practices of generalist primary school teachers, often frequently based on a narrow range of learning activities and relying on individual practitioners’ experience with classroom technology. Copland et al (2014) identify both global trends and local specificities to be considered in the design and evaluation of new learning scenarios, and challenges for virtual language learning are related to both the classroom context (Enever & Moon, 2009) and the broader teaching culture (Jin & Cortazzi, 2003). Drawing on data from an ongoing nationally funded project on the co-construction of interactive virtual learning scenarios for primary EFL teaching in France, this paper asks to what extent a collaborative research project involving EFL and education researchers, primary school teachers, and teacher educators can support an approach to evaluation which both fosters professional development in EFL teaching and adds to our understanding of how such development arises. Data from 9 primary classes include pre- and post-intervention learner surveys, classroom films, teacher and learner interviews, and post-intervention teacher focus groups; analysis sheds light on the challenges of an ecological evaluation (Younès, 2019) requiring the activation of interdisciplinary, dialogical, and personal synergies.