Teaching a new conceptual framework of weight and gravitation in middle school

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 = 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.