In recent years, a growing body of international /European comparative research on teaching, learning, and didactics has been published (Hudson & Meyer, 2011; Hallizky et al., 2016; Ligozat et al., 2023). Empirical comparative research into classrooms has identified patterns of instructional strategies that differ across countries (e.g., the TIMSS 1995 video study, Stigler et al. 1999)). The research has demonstrated that there are national and cultural differences regarding the conceptualisation of academic knowledge about teaching and their role in teacher education depending on the national and cultural context (cf. Rakhkochkine 2012). Despite the persistent fragmentation among national and regional traditions of teaching and learning, there is a noticeable trend toward the universalization and even standardization of subject-specific didactic approaches and teaching practices. This trend is driven by factors such as international student assessment studies, the processes of lending and borrowing educational practices, globalization in the production of teaching materials, internationalization in teacher education, and international teacher mobility. One of the recent trends in education, which gained momentum during the COVID-19 pandemic, is platformization. Platforms have impacted many spheres of economic and social life, and education is no exception. According to Kerssens & Van Dijck (2021), the transformation of educational content, activities, and processes means that they become part of a corporate platform ecosystem, including its economies, data infrastructures, and technical architectures. Global platforms contribute to the commodification, globalization, and privatization of educational provision (Kerssens & Van Dijck, 2023). The platforms seem to have impact on the teacher professionalism by fostering predefined topics and teaching strategies. Based on their analylis of the European platform eTwinning, Lewis and Decuypere conclude: "Rather than merely seeing the platform as a passive or neutral vehicle for hosting projects, we would instead suggest that eTwinning provides an exemplary environment for repositioning project thinking as a central, and even necessary, aspect of teacher professionality" (Lewis & Decuypere 2023, 41). This paper explores the research question of how different national and cultural traditions in didactics are negotiated and transformed within the transnational virtual spaces of educational platforms:  What are the main characteristics of the transnational didactics on eTwinning (in particular in comparison to the national traditions of didactics also to the national traditions of digital teaching and learning) and how does this didactics develop or is developed (in collaborative interactions, modified by technical framework of the platform, depending on partner selection, both at the levels of general and tertiary education)?

The first part of the paper presents a theoretical analysis (literature review) of research into national traditions of teaching, learning, and didactics from a comparative perspective, with a particular focus on transnational curriculum and didactics, as well as platformization in education. The second part of the paper is based on a small-scale study that make a step beyond the theoretical reflections and explores the possibilities for empirical research by examining collaborative projects in eTwinning (a European platform for cooperation between schools and institutions of teacher education), developed and implemented in teacher education. These projects are an integral part of the internationalization of teacher education in participating countries. It applies document analysis (project descriptions and reports) and interviews with developers and participants of an eTwinning project.

The paper seeks to identify the characteristics of the emerging transnational didactics in eTwinning, particularly in comparison to national traditions of didactics and digital teaching and learning and discusses intended and unintended effects of platform-based internationalization on teaching and learning. It argues that the platform has a standardising impact on the selection of goals and the content of teaching and learning, the language of instruction and co-operation, the teaching methods and assessment that is related more to the objectives of the projects and less to the national assessment schemes.

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