Physics curriculum of middle school and high school is based on the classic perspective of the 19th century and avoids dealing with the concept of observer (frame of reference). This by far holds regarding the curriculum of middle school, as even though it includes numerous observer-dependent concepts (location, trajectory, displacement, velocity, force, energy, work), it entirely excludes observer and observer dependent description of reality, and they are not taught as such. This tradition apparently draws on the assumption that students are incapable of learning observer dependent concepts because that requires an account with multiple answers valid for different observers. For that reason it is considered to be as a sort of advanced subject matter that should be treated at higher education level. We empirically checked this convention and discovered that 9th grade students succeeded in applying frame of reference dependence to their accounts of daily experiences. For example, they were able to construct graphs expressing dependence of displacement, distance, and velocity on time in the perspective of different inertial frames of references. The results clearly indicate that integrated observer-dependent concepts in middle school promises substantial educational and pedagogical benefits (e.g. wider space of learning, intuitively and meaningful learning, students’ engagement and adequate image of science).

This study deals with the concept of the observer in science education, which is currently significantly diminished at school. In the first part, we review the theoretical perspective of the concept, regarding its historical role in physics knowledge, cognitive aspects of learning and the relevant curricular situation. The second part of the study was devoted to the experiment, which included constructing new materials to facilitate interpretation of physical situations by inertial and non-inertial observers in teaching students in middle schools. The impact of the experimental teaching was assessed by an open questionnaire addressing content knowledge and affective perception of the new material. The significant positive results obtained testify to the feasibility of such innovative teaching. It has a strong advantage in comparison with the control group. The implication of the study could be significant changes which would upgrade school physics curricula. The explicit inclusion of the inertial forces—instead of banning them, as currently practised—maturates the physics knowledge of school students.