Abstract
This study reports on an investigation of students' understanding of the concept of weightlessness among intermediate, high school and college students. It appears possible to interpret this knowledge as being highly influenced by the confusion between two basic physics concepts, weight and gravitational force, which are often equated in a standard physics curriculum. The proposed causal structure of students' knowledge presents a platform for interpreting a cluster of students' alternative ideas about weight and related physical concepts. This platform could guide physics educators in their considerations of appropriate strategies for presenting weight and gravity topics in the classroom.
