The roles of conceptual change and model building in science education are very important and have a profound and wide effect on teaching science. This study examines the change in children's position concepts after instruction, based on different conceptual change theories. Three classes were chosen and divided into three groups, including a model implicating group (n = 29), a conceptual conflict group (n = 31), and a model building group (n = 30). The researchers used a two-tier diagnostic instrument to inquire position concepts for elementary school students and interviews for gathering students' concepts. This study applies one-way ANCOVA (analysis of covariance) for data analysis. Results indicate that the three groups can improve their high-order understanding of the position concepts. The score of the model building group was significantly higher than that of the model implicating group. (Contains 5 tables and 4 figures.)