Solution Learning Using Colloids Effectively in Lower Secondary School

Abstract

The uniformity of solutions is a fundamental aspect of solution understanding. However, it is not easy to understand it even after repeated learning in the fifth grade of elementary school and the first grade of lower secondary school. To overcome this problem, our study aims to develop a teaching strategy for a reliable understanding of the uniformity of solutions. With this aim in mind, we propose a lesson on colloidal solutions as one of the pillars of solution study, in which the students must think about liquids through a comparison of the following three categories. (A) Clear, aqueous solutions. (B) Overall cloudy colloidal solution. (C) The suspension in which the particles sink. In this lesson, students will experimentally clarify that the difference between these liquids is a difference in the size of the particles in the liquid. Furthermore, students will clarify the reason for the overall cloudiness of (B) the colloidal solution (paint solution) by observing Brownian motion. Students will combine these activities, compare, and discuss the uniformity of aqueous solutions. As a result of the practice of this class in the first grade of lower secondary school, the students showed great interest in the class and performed well on a test on solution uniformity. Moreover, they were able to maintain high grades in their examinations on this topic in their second year. This suggests that the understanding of solution homogeneity is well established. This lesson and method was thus confirmed to be effective to promote solid understanding of the uniformity of solutions among elementary and junior high school students.