electricity, such as “voltage”, “electric current”, “resistance”, and “electric power”, according to the strict definitions of the scientific model, even when these concepts have been explained to them in class. Instead, they use other concepts, such as “force” or “energy”, which seem to be more familiar to them. However, there are not many studies focusing on evolutionary concept-construction that have as a starting point the alternative ideas students, at different ages, have for each of the above mentioned concepts of electricity. In this study we attempt to fill this gap by an empirical investigation of the conceptual change that occurs during the construction of electricity concepts in school time.
The theoretical investigation of student misconceptions gave rise to the assumption that the alternative ideas through which they understand the above electricity concepts can be classified in two levels, while in a third level we can place the scientific model. In accordance to this classification it is highly possible that electricity concept construction originates from certain actually experienced objects, whereas the understanding of natural changes is located in the present, it is associated to the notion of force and it refers to the intensity of the phenomenon under examination. Later on and under the influence of instruction, students start grasping these concepts through notions of the microcosm, while natural changes can be conceived as evolving in time, they are associated to the notion of energy and they are related to the duration of the phenomenon in question. Our sample consisted of 433 students aged 11, 13, 15 and 17. They were asked to fill paper and pencil questionnaires on the meaning of each of aforementioned concepts. Their answers were processed by the hierarchical cluster analysis method. It was found that to each concept corresponded four modes of its understanding that constituted phases of a developmental sequence. In particular, the two levels of alternative ideas were identified in all age groups, although with lesser frequency in older students. In addition, the scientific model was present in younger age groups as well, due to the influence of instruction, but it tended to increase as we moved towards older age groups.