Measuring Students’ Scientific Argumentation Associated with Uncertain Current Science

In this study, we investigate how students’ claim, justification, uncertainty qualifier, and conditions of rebuttal contribute to the measurement of their overall scientific argumentation ability. We designed six sets of items related to climate change and the search for life on other planets. The items were administered to 956 students taught by 12 middle and high school teachers in the Northeastern United States. Rasch analysis results based on the Partial Credit Model indicate that (1) students’ responses to all four argumentation elements can be interpreted on a single scale, (2) higher scientific argumentation abilities are needed in the order of uncertainty qualifier, claim, justification, and conditions of rebuttal on the scientific argumentation scale, (3) justification and conditions of rebuttal items measure a wider range of the scientific argumentation scale than claim and uncertainty items, (4) students who make a single warrant are more likely to think about conditions of rebuttal within the context of investigation, and (5) students who make two or more warrants are more likely to consider conditions of rebuttal beyond the context of investigation. We discuss these results to refine Toulmin’s theory, provide recommendations for designing and implementing large scale assessment, and suggest future research directions.