With the increasing presence of new media, life in classrooms all around the world has drastically changed. The critical and conscious use of media messages provided by technological devices has developed into a crucial 21st century skill. Lin et al. (2013) have laid ground for a useful and proven theoretical framework regarding media literacy. Based on the concept of presuming and consuming media in a critical or functional way, the authors suggest ten fine-grained
indicators to define new media literacy (Lin et al., 2013). Building onto this framework, recent academic research discusses the concept of new media, media literacy and the importance of implementing adequate courses in curricula (Koc & Barut, 2016; Zhu et al., 2020). However, the development of an apt way to test media literacy is still a great challenge for secondary education.

After conducting an extensive search in scientific literature, it turns out that there is no usable, validated tool for a precise measurement of media literacy as a 21st century skill in secondary education. Researchers have been able to construct definitions, frameworks and questionnaires (Zhu et al., 2020), but a validated instrument to test and check the precise development of a specific skillset is still lacking. The aim of this developmental research is therefore to draw up an instrument to measure the mastery of various, specific components of media literacy in secondary education. An adequate tool to be able to formatively test these skills would be a rubric with a five-point scoring scale: it can help teachers to better understand their students' skills and progress in media literacy, and in addition, it gives students insight into specific learning outcomes that have to be achieved.

The development of this rubric is conducted through an iterative process in which results are regularly tested through experiments in educational practice. In this process, the targeted audience consists of not only teachers but students, advisors and researchers as well. With this instrument, the use of specific workshops and courses and can be tested on efficiency. By letting teachers (and students) use this rubric as a guideline, it is possible to assess whether students structurally develop better mastery of media literacy after following specific workshops or courses. Through use of this crucial tool, media literacy can therefore be more fully integrated within the curricula of secondary education.