This study reports the impact of Recurrent On-Line Synchronous Scientific Argumentation learning on 8th grade students' scientific argumentation ability and conceptual change involving physical science. The control group (N = 76) were recruited to receive conventional instruction whereas the experimental group (N = 74) received the Recurrent On-Line Synchronous Scientific Argumentation program for about 25 physical science class periods of 45 minutes each, which is about one third of the physical science class periods in a semester. Results indicate that the experimental group significantly outperformed the conventional group on the post-Physical Science Conception Test and the Physical Science Dependent Argumentation Test. The quantity and quality of scientific arguments that the experimental group's students generated, in a series of pre- and post-argumentation questions, all improved across the seven topics. In addition, the experimental group's students successfully constructed more correct conceptions from pre- to post-argumentation questions across the seven topics. This clearly demonstrates that the experimental group's students' argumentation ability and conceptual change were both facilitated through receiving the Recurrent On-Line Synchronous Scientific Argumentation program. (Contains 4 tables and 4 figures.)