To frame the genesis of instruments to capture the digital competence of pre-service teachers and, in particular, instruments which involve reasoning for or against digital technology (dTs) and the facet of “selecting digital learning materials”, we first provide the conventions used to describe “digital resources” in education. Further, we examine two definitions of “competence” in educational research, one by Blömeke et al. (2015), and another by Weinert (1999). Additionally, we decompose the “digital competence” of (pre-service) teachers using the DigCompEdu framework and a localized German Delphi study defining the digital competence of pre-service teachers from the perspective of STEM teacher educators.