No abstract

No abstract

No abstract

Empirical studies have reported difficulties, confusion, and lack of understanding among students at all levels of instruction regarding the issue of weight-gravitation-weighing relationships. This study examined the impact of a new conceptual framework of weight, on a small group of 7th-grade students (N ¼ 14) in a middle school in Israel. This conceptual framework, which defined weight operationally as weighing results, implied a natural distinction between weight and gravitational force, in contrast to the gravitational definition of weight, which identifies these two concepts. The new framework not only better fits modern scientific epistemology but also matches the common intuitive conception of weight as representing the heaviness of objects. This coherence promises innovative teaching leading to easier and more meaningful learning. The applied pedagogical method included a historical excurse and knowledge mediation through a discursive mode of teaching using images of different environments (Thinking Journey). The collected data of students' knowledge were structured in terms of scheme-facets of knowledge, which allowed qualitative evaluation of knowledge changes due to the instruction. We found that discussion of the lunar environment led students to appreciate the universality of gravitational attraction and to develop operational meaning for the up-down direction. Considering the environment of a coasting satellite encouraged students to distinguish between the gravitational force causing the orbiting around the Earth, and weight as the force that objects naturally exert on their support. It appeared that falling served as an anchoring concept leading students to the operational definition of weight. #

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).