In 2022, Berlin`s regional teacher training institution started a voluntary course in blended learning for vocational schools. Members of Humboldt-University joined with further education multipliers for digitalization to develop this course as an educational design research project (cf. McKenney/Reeves 2018, see "Methodology"), tailored to teacher's needs and the status quo in vocational schools in Berlin, Germany. This paper will delineate the development and evaluation of this training, with a special focus on mapping the diverse types and forms of knowledge (cf. Goldkuhl 2020; Johannesson/Perjons 2014) which informed both the design and the theoretical understanding obtained from it.
The demand for such a teacher training was based on lessons learned during the COVID19 pandemic's lockdowns and emergency remote teaching (cf. Hodges et al. 2020). Evidently, online learning environments and digital media allow for new educational settings with the potential to increase and innovate learning effects (cf. Müller/Mildenberger 2021). However, technologies and the respective legislatures are developing at a rapid pace (e.g. the European Data Protection Regulation, https://gdpr.eu/), so teachers on-the-job need further training to acquire "an increasingly broad and more sophisticated set of competences" (cf. the European DigiCompEdu framework, Redecker 2017, p. iv). Also, current generations of learners use media in very different ways and for very different objectives than their teachers do (cf. Khan/Vuopala 2019; Feierabend et al. 2017), calling for a reflection and redefinition of media competences for both groups. Focusing on vocational education, "new work" increasingly relies on digital media and specific vocational competences (cf. Rafiola et al. 2020), which cannot be expected to be covered by current curricula yet.
  
At the same time, a number of challenges considering online learning have been discovered. It has been evident throughout the COVID19 pandemic that on-site teaching still has substantial advantages over online teaching. Particularly, schools serve custodial and social functions: They offer students a range of possibilities to meet with and emotionally grow among peers in complex social situations. Also, schools supervise learners on behalf of parents and other custodians. This "baby sitter" function, as Wall (1978) put it cynically, is a socioeconomic prerequisite for most families to partake in work life (as experienced by many in a very stressful way during COVID19 lockdowns). Goudeau et al. (2021) summarize how school closures and remote teaching with predominantly digital resources exacerbated social class disparities in three ways: the digital divide (learners` unequal access to digital resources, tools and skills), the cultural divide (unequal familiarity with academic knowledge and skills; unequal dispositions for autonomy and self-regulation), and the structural divide (unequal support of learners from schools). In addition, concerning vocational education with its many lab and workshop settings, hands-on and on-site learning are still understood to be indispensable for the development of practical work skills, which in turn have an effect on students' employability. 
In consequence, it is not "pure" online learning but deliberate "blended learning" which is of considerable importance for vocational schools, teachers and learners. "Blended learning" can be defined as "a formal education program in which a student learns at least in part through online delivery of content and instruction with some element of student control over time, place, path, and/or pace and at least in part at a supervised brick-and-mortar location away from home." (Staker/Horn 2012, p. 3) Teachers who want to develop blended learning programs then need some specific competences, which both include and exceed the respective competences for online and on-site elements of their programs. The design research project "Blending 4 Futures" aimed at identifying such competences while developing a suitable teacher training course, as shown in the "Findings" section.

As educational design research aims to combine a specific "maturing intervention" with general "theoretical understanding" (cf. McKenney/Reeves 2018), the course development was conducted as an agile, iterative process based on collaborative work and formative feedback. In a "practice what you preach" approach to blended learning, both the development process and the final course deliberately blended online and on-site activities. The participating teachers learned how to develop blended learning programs for their respective target groups of students of different vocations, while partaking in a blended learning training format themselves. Thus, participating teachers could experience blended learning both from the perspectives of learners and of developers. In effect, trainers, researchers and participants constantly reflected on conditions, factors and principles of successful blended learning, in an agile mindset of (re-)designing the course as it progressed. Inspired by Sandovals (2014) concept of "conjecture mapping" for design research, a "knowledge map" was created to illustrate the various types and forms of knowledge informing the design and being obtained from it as in- and outflows. Data for this was collected via desktop research, document analysis, and formative and summative feedbacks both during design meetings (concerning the involved teacher trainers) and during training sessions (concerning the participating teachers). As a learning management system, Berlin's central Moodle platform "Lernraum Berlin" was used, offering the developers diverse tools for collaboration and evaluation, such as etherpads, video calls and anonymized survey tools. McKenney/Reeves (2018) propose a three phase process model with iterations for educational design research. This model was referenced to structure both the design project and the "knowledge map" as one of its results. These phases are 1. "Analysis and Exploration", 2. "Design and Construction", and 3. "Evaluation and Reflection", plus a parallel dimension of increasing (4.) "Implementation and Spread". Depending on the phases, the types and forms of knowledge varied and where differentiated according to the typologies of Goldkuhl (2020) and Johannesson/Perjons (2014). For example, during "Analysis and Exploration", relevant knowledge tended to be "explicit" in the form of published literature and "embodied" in the form of participants' teaching experience and best practice. During "Evaluation and Reflection", though, relevant knowledge tended to be "embedded" in the form of design artefacts, such as blended learning concept documents, learning management system courses, and teaching materials/learning media.

In line with McKenney/Reeves (2018), the project results include both the realized designs and theoretical understanding, especially transferrable design principles. The prototypical design includes a written concept, a "navigator" visualizing the events-and-tasks structure of the course, and the rexpective learning media. The format of the written concept can be understood as an emerged standard template for blended learning in vocational schools, which was also applied by the participating teachers in order to develop their own blended learning prototypes for students. The parameters of this template are: 1) (Working) Title of the program (foreshadowing both content and methods) 2) Curriculum Context (when and why to teach) 3) Learning Objectives (integrating vocational and media competences) 4) Vocational Core (vocational problems, processes and products learners will encounter) 5) Progression Concept (events-and-tasks-structures as well as the logic of transitions between elements) 6) Supervision Concept (supportive moderating, coaching, social and custodian activities) 7) Lessons Learned and Development Ideas (incorporating an ongoing re-design of the concept based on teaching experience and student feedback) The authors conclude that the two conceptual factors "Progression Concept" and "Supervision Concept" with their respective competences are the distinguishing factors of a specific "blended learning competence", surpassing those media and methods competences which teachers already need for "pure" online or on-site education. When deliberately blending online and on-site education, new challenges of progression and transition emerge, such as: how to transfer outcomes of online activities to on-site activities, how to arrange and communicate mandatory and self-organized elements etc. Challenges of supervision arise from attendance legislature (especially supervision in labs and workshops), e-moderating (cf. Salmon 2011, p. 60ff), communication and feedback needs, differentiated support needed to reduce socioeconomic inequalities, etc. “Progression" and "supervision" thus hint at specific challenges (and design principles) which distinguish blended learning in vocational schools from other educational settings.

Feierabend, Plankenhorn, and Rathgeb (2017), JIM 2017. Jugend, Information, (Multi-)Media. Basisstudie zum Medienumgang 12- bis 19-Jähriger in Deutschland, mpfs, Stuttgart. GDPR - General Data Protection Regulation: https://gdpr.eu/ Goldkuhl, Göran (2020): Design Science Epistemology. A pragmatist inquiry. In: Scandinavian Journal of Information Systems 32 (1), Paper 2. Online: https://aisel.aisnet.org/sjis/vol32/iss1/2. Goudeau, S., Sanrey, C., Stanczak, A., Manstead, A., & Darnon, C. (2021). Why lockdown and distance learning during the COVID-19 pandemic are likely to increase the social class achievement gap. Nature Human Behaviour, 5 (10), 1273-1281. Johannesson, Paul; Perjons, Erik (2014): An Introduction to Design Science. Cham: Springer. Khan, F., & Vuopala, E. (2019). Digital competence assessment across generations: A finnish sample using the digcomp framework. International Journal of Digital Literacy and Digital Competence (IJDLDC), 10 (2), 15-28. McKenney, Susan; Reeves, Thomas C. (2018): Conducting educational design research. 2. Ed. London, New York: Routledge Taylor & Francis Group. Müller, C., & Mildenberger, T. (2021). Facilitating flexible learning by replacing classroom time with an online learning environment: A systematic review of blended learning in higher education. Educational Research Review, 34, 100394. Rafiola, R., Setyosari, P., Radjah, C., & Ramli, M. (2020). The effect of learning motivation, self-efficacy, and blended learning on students’ achievement in the industrial revolution 4.0. International Journal of Emerging Technologies in Learning (iJET), 15 (8), 71-82. Redecker, Christine (2017): European framework for the digital competence of educators. DigCompEdu. (Ed. Yves Punie) Luxembourg: Publications Office of the European Union. Reinmann, Gabi (2011): Blended Learning in der Lehrerausbildung: Didaktische Grundlagen am Beispiel der Lehrkompetenzförderung. In: Seminar (3), p. 7–16. Salmon, Gilly (2011): E-moderating. The key to online teaching and learning. 3. Ed. London: Routledge. Sandoval, William (2014): Conjecture Mapping. An Approach to Systematic Educational Design Research. In: Journal of the Learning Sciences 23 (1), p. 18–36. DOI: 10.1080/10508406.2013.778204. Staker, Heather; Horn, Michael B. (2012): Classifying K–12 Blended Learning. Hg. v. Innosight Institute, Inc. Hodges, Charles; Moore, Stephanie; Lockee, Barb; Trust, Torrey; Bond, Aaron (2020): The Difference Between Emergency Remote Teaching and Online Learning. Online: https://er.educause.edu/articles/2020/3/the-difference-between-emergency-remote-teaching-and-online-learning (23.09.2020). Wall, Donald G. (1978): Minimizing the Custodial Function of the School. In: NASSP Bulletin 62 (416), S. 41–48.