Purpose: Attempts to cultivate a multilingual mindset in education in South Tyrol find an obstacle in educational norms, structures and policies that divide students into linguistically distinct schools based on their self-identified main language. Education in the region is administered through three separate educational authorities -- German-speaking, Italian-speaking, Ladin-speaking -- and teachers are prepared for service in one of these based on their own declared linguistic identification. Plural identities and translingual interaction do not flourish in this context where language separation is the norm. This paper begins with an overview of the educational policy of language separation in South Tyrol and its impact on the language achievement of its students. It then addresses how the Free University of Bolzano has responded to the need for improved language competences through teacher training for multilingual schools in the Province of Bolzano. Design: The paper presents the preliminary results of a small-scale study with in-service preschool teachers through an action research cycle in which classroom observations and a language input observation scheme are used to quantitively measure the quality of teachers' language input in second-language instruction in German and English, and provide formative feedback for improvement in teaching practice. Findings and Value: The expected outcomes of the study are threefold: (1) improving input and corrective feedback strategies of language teachers; (2) raising language awareness among teachers participating in peer observation; (3) empowering the emergence of language rich episodes through effective planning of interactive lessons in second/foreign language teaching. The study contributes to an understanding of what makes teachers' corrective feedback strategies in preschool settings effective in rendering input comprehensible for young learners, thus assisting language appropriation processes.