• physical science;
  • cooperative grouping;
  • technology education/software design


The national science standards, along with prominent researchers, call for increased focus on scientific argumentation in the classroom. Over the past decade, researchers have developed sophisticated online science learning environments to support these opportunities for scientific argumentation. Assessing the quality of dialogic argumentation, however, has proven challenging. Existing analytic frameworks assess dialogic argumentation in terms of the nature of students' discourse, formal argumentation structure, interactions, and epistemic forms of reasoning. Few frameworks, however, connect these assessments to conceptual quality. We present an analytic framework for assessing argumentation in online science learning environments that relates levels of opposition with discourse moves, use of grounds, and conceptual quality. We then apply the proposed framework to students' dialogic argumentation within a representative online science learning environment to investigate the framework's potential affordances as well as to assess issues of reliability and appropriateness. The results suggest that the framework offers significant affordances and that it also offers high interrater reliability for trained coders. The applicability of the framework for offline contexts and future extensions of the framework are discussed in light of these results. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 45: 293–321, 2008