Diagnosing the Cognitive Structure of Photosynthesis Concept: Using the Word Association Method and Concept Relations Task

Abstract

The photosynthesis is one of the most important concepts in the biology education, but is difficult one for the student to understand. According to Ausubel, to promote student's learning of scientific concepts, it is important to ascertain the cognitive structure which he already has had, and to teach in accordance with it. However, the student's existing cognitive structure about photosynthesis concept isn't made to be clear enough. Then, the purpose of this paper is to clarify this structure from following two points: the strength of connection among concepts in the cognitive structure and the reason of those connections. Firstly, the related 11 concepts to photosynthesis (i.e., the nutrition, the energy, the light, the chemical reaction, the water, the carbon dioxide, the oxygen, the chloroplast, the organic compound, the enzyme, and the respiration) are selected. Next, the subjects (76 students in the upper secondary school) are divided into two groups. In one group, the strength of connection between photosynthesis concept and one of those selected concepts is examined by the word association method. In another group, the reason of this connection is investigated by concept relations task. The findings are summarized as the following: 1. The connections of the photosynthesis with the chloroplast, the oxygen, and the light are strong. 2. The connections with the carbon dioxide, the chemical reaction, and the enzyme are weak. 3. The reasons of those connections which the subjects described are often inappropriate. From these findings, it is considered that the subjects generally incline to think that photosynthesis is the process which needs the light, takes place at the chloroplast, absorbs the carbon dioxide, and releases the oxygen. It is clarified that they don't recognize integratedly the photosynthesis concept in terms of the nutrition and the energy.