Every person is confronted with multiple usage decisions, especially in the context of digital systems. The challenge for computing education is to enable students to make these decisions in an “informed” manner, which is considered a key competence needed to become a responsible citizen. As a first step within our research project, we report an attempt, inspired by healthcare research, to measure informed usage decisions by calculating a score indicating the “informedness” of a decision. We evaluate and discuss our method based on a first findings from a field test with 28 students.