Characterizing Uncertainty Associated with Middle School Students’ Scientific Arguments

In this study, we investigated how students’ claim, justification, uncertainty, and conditions of rebuttal contribute to the measurement of the overall scientific argumentation ability. We designed six sets of items, each of which consisted of claim, justification, uncertainty rating, and conditions of rebuttal items. These item sets addressed six investigations related to climate change and extraterrestrial life. We administered them to 956 students from 12 middle and high school teachers. We applied descriptive statistics and a Rasch Partial Credit Model analysis. Results of descriptive statistics show that students’ difficulty in justifying their claims with scientifically valid warrants and in scientifically considering conditions of rebuttal that might undermine the strength of their argument. Rasch analysis results indicate that (1) all items can form a single scale, (2) students’ scientific argumentation ability is represented in the order of uncertainty, claim, justification, and conditions of rebuttal, (3) justifications and conditions of rebuttal probe wider ranges of the scientific argumentation construct than claims and uncertainty ratings, (4) students who are able to 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. Scientific argumentation construct 3