Abstract
The purpose of this study was to examine the effectiveness of a lesson plan based on two principles, the transition from intuitive judgment of salt concentration to quantitative judgment based on a proportion, and were abstracted from concrete definitions to general ones. The effectiveness of the lesson plan was evaluated based on the post-evaluation tasks, the follow-up tasks, and the learners' observations during the lessons. Analysis of 25 fifth graders showed that on the post-evaluation tasks, the rate of correct responses exceeded 80%. However, in the follow-up tasks conducted four months after the end of the class, the formulas were scarcely applied, and when solving the problem using proportions, many learners were confused between the ratio and the comparison amount. Analysis of the lesson process showed that the “size per unit amount” in the lesson was not sufficiently distinguished from the ratio, which might have caused confusion.
