Abstract
In this study, we investigated lower secondary student's understanding about dissolving. Sixteen students of the 8th grade were interviewed using "Contradiction-Explanation Method." The results were as follows. The ontological presupposition that unsupported objects fall downwards, was crucial base of student's understanding about dissolving. Subjects showed four types of conceptual integration of their ontological reasoning with scientific reasoning. Furthermore, the developmental trajectory was proposed in knowledge acquisition about the uniformity of solution. Finally, the implications of these results for science education were briefly discussed.
