Children's models of the ozone layer and ozone depletion

Abstract

The views of forty primary students about ozone and its depletion were recorded through individual, semi-structured interviews. The data analysis resulted in the formation of a limited number of models concerning the distribution and role of ozone in the atmosphere, the ozone depletion process, and the consequences of ozone depletion. Children's models involve a variety of alternative conceptions which indicate the presence of a number of different target obstacles; that is, critical factors constraining children's understanding and thus preventing the construction of adequate models. Five target obstacles were identified: (1) the lack of conceptual distinction between ultraviolet and other forms of solar radiation; (2) the lack of the absorption mechanism of ultraviolet rays by ozone; (3) the conceptualisation of the atmosphere as an entirely homogeneous mixture of its constituent gases; (4) the non-localisation of the ozone layer around the earth; and (5) the lack of interpretation of the ozone hole as a decrease in the concentration of ozone. The identification of those target obstacles constitutes the first step for the design and evaluation of appropriate teaching aims and material.