The purpose of this study was to investigate the effects of conceptual change-oriented instruction through demonstrations (CCOITD) on 11th grade students' understanding of rate of reaction concepts when compared to traditionally designed chemistry instruction (TDCI). The sample consisted of 69 11th grade students from two classes in a public high school. Reaction Rate Concept Test was administered to both groups as a pretest and posttest to assess students' understanding of the concepts. The data was analyzed by using one-way ANOVA. The results show that the experimental group in which CCOITD used had a significantly better acquisition of scientific conceptions related to rate of reaction than the control group.