2023 Volume 64 Issue 1 Pages 51-62
The purpose of this study was to clarify the difficulties lower secondary school students experience in expressing chemical changes in terms of chemical reaction formulas, and to verify the effectiveness of classes introducing “Material Model Cards” in overcoming this difficulty. To determine the former, a survey about chemical equations and chemical reaction formulas was conducted among ninth grade students. The survey results suggested that students experienced difficulties in understanding the meaning of chemical information, given their levels of knowledge and reasoning powers, when chemical reactions were expressed by chemical reaction equations. To determine the latter, a class in which students manipulated “Material Model Cards” and a class in which they drew “models of atoms and molecules” was conducted with eighth grade students in two classes, one of which served as a control group while the other, experimental group, utilized the new teaching material. A post-class survey regarding chemical formulas and chemical reaction equations showed no difference in the effect on the experimental group and the control group upon the representation of chemical changes in terms of chemical reaction equations. However, in the delayed survey, significantly more students in the experimental group were able to express chemical changes in terms of chemical reaction formulas. Students who were able to express chemical reaction formulas in the post-class survey were subsequently classified into those who were, or were not, able to do so in the delayed survey. These results of the delayed survey of the classified students were compared, and from the results it was inferred that the lesson in which students were asked to manipulate the “Material Model Cards” was indeed effective in helping students retain knowledge required to represent chemical changes in chemical reaction formulas.
