Language immersion education, stemming from Canadian immersion programmes in the 1960s, has gained global traction, shaped by varied sociolinguistic landscapes. While these programmes differ in languages used, goals, and target audiences, research consistently shows that immersion is an effective approach for teaching languages and content without compromising students' first language. In Ireland, Irish-medium education (IME) strives for additive bilingualism and cultural preservation. Despite its expansion, IME struggles with challenges in implementation and concerns about effectiveness. Research over the decades has consistently shown that IME students’ productive language skills often deviate from language norms in areas such as grammatical accuracy and complexity, lexical specificity, phonological patterns, and sociolinguistic appropriateness. Research indicates that difficulties in IME students’ language development can partly stem from teachers' lack of language knowledge. While there is wide agreement that immersion teaching requires a specialised knowledge, few attempts have been made to conceptualise the language knowledge required for successful content and language integration. Drawing on Morton’s (2016) framework on language knowledge for content teaching, this study identifies critical language knowledge domains for IME teachers in Ireland. Utilising interviews and questionnaires, stakeholders' viewpoints illuminate the intricate nature of IME teacher language knowledge. The findings underscore the significance of specialised language knowledge for immersion educators, offering insights to enhance practice and meet the needs of IME learners. This research contributes to navigating the evolving landscape of immersion education, fostering its advancement in Ireland and beyond.

References:
[1] Morton, T. (2016). Conceptualizing and investigating teachers’ knowledge for integrating content and language in content-based Instruction. Journal of Immersion and Content-Based Language Education 4 (2): 144–167.

Keywords: Immersion education, teacher knowledge, professional development.