This paper discusses the relationship between "Whole-class discourse" and "Local discourse" and describes how students make sense of science through local discourse. The following two trends were identified: 1. Many students engaged in Local discourse. 2. Local discourse helped students resolve cognitive conflicts. The results of this study show how understanding of science can be enhanced through active local discourse among students. The whole class became a kind of science community when a connection was made between Local discourse and Whole-class discourse.