Models of Students' Thinking Concerning the Greenhouse Effect and Teaching Implications

Individual, semistructured interviews were used to study 40 primary school students' (ages between 11 and 12 years) conceptions concerning the greenhouse effect. Analysis of the data led to the formation of 7 distinct models of thinking regarding this environmental phenomenon. The inferred models are differentiated according to the following criteria: (a) the position and distribution of the greenhouse gases; (b) the existence of connections between the greenhouse effect and the ozone layer, or its depletion; and (c) the types of radiation considered to be involved in the greenhouse effect. Children's models involve a common core of beliefs, according to which the greenhouse effect is due to solar radiation that heats up the earth and the atmosphere, while getting trapped by certain atmospheric gases, and severely changes the climate, melts the polar ice, and raises the sea level. The teaching implications discussed are: (a) the concept of uniform diffusion of atmospheric gases; (b) the conceptual distinction between ultraviolet and other forms of solar radiation; (c) the conceptual distinction between sunlight and terrestrial radiation; and (d) the conceptual distinction between the roles of the ozone layer and greenhouse gases in the atmosphere.