## 1 Introduction  
The use of various technologies to enhance education, the field of technology-enhanced learning (TEL), is nowadays widespread. The motivations for this progress are manifold. For instance, [PERSON], [PERSON], and [PERSON] [1] identified in a literature review several publications that give reasons for the necessity of technology-enhanced learning approaches. On the whole, the identified publications claim that these approaches are required for living and working in our digital economy, and since people are used to using technologies in their life, they demand learning scenarios that apply those technologies. The term technology-enhanced learning itself is the most widespread term in this field and combines all approaches in which technology is used to support the learning or teaching process. Thus, terms like e-learning and online learning, as well as more specialized fields such as game-based learning, web-based learning, and others, are part of the research field of technology-enhanced learning [2]. This definition of the term technology-enhanced learning also implies that the research area is vast, and when successfully implementing technology-enhanced learning approaches different aspects have to be considered. However, there are only a few methodologies that support this structured development of individual and successful approaches. In the following, selected methodologies and the aspects addressed in these methodologies are described briefly. [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] [3] address the issue as learn service engineering. They suggest that technology-enhanced learning approaches should be treated as services. In this way a structured development, comparable to the engineering discipline of service engineering [4], is possible. In doing so, [PERSON] _et al._[3] consider four main views: economic aspects, technical aspects, didactic aspects, and general organizational conditions. Another generic methodology looks especially at the development process itself and considers the four stages of planning, implementing, controlling, and improving, whereby learning outcomes are used as control variables [5], and an even more generic model observes pedagogical, social, and technological perspectives [6]. The issue of the structured development of e- and m-learning was also considered within the Europe-wide project UNITE. In the project, a pedagogical framework was evaluated that considers five components: pedagogical framework context, pedagogical approaches, assessment techniques, current pedagogical practices implemented in national curricula and national specifics, and teacher training [7]. [PERSON], [PERSON], and [PERSON] [8] show a more detailed model to develop effective e-learning for teaching a coding language. First, they divide the process into five phases: analysis, design, implementation, execution, and evaluation. Second, during each phase they consider the following aspects: perception, attention, cognitive load, coding, retrieval/transfer, and metacognition. Furthermore, focused on the development of online learning programs and to determine their success, [PERSON] and [PERSON] [9] suggest taking seven important factors into account: planning, marketing and recruitment, financial management, quality assurance, student retention, faculty development, and online course design and pedagogy. As can be seen, the considered aspects in these models are not unified and none of the above methodologies include all possible facets that are investigated in the research field of technology-enhanced learning. This led to the following research question:What aspects could possibly be considered when implementing technology-enhanced learning approaches? The answer to this question is given by a large-scale literature review identifying aspects examined in the research area of technology-enhanced learning that could be considered when implementing approaches to TEL.