Using a case study method, the experiences of a group of high school science teachers participating in a unique professional development method involving an argue-to-learn intervention were examined. The participants (N = 42) represented 25 different high schools from a large urban school district in the southwestern United States. Data sources included a multiple-choice science content test and artifacts from a capstone argument project. Findings indicate although it was intended for the curriculum to be a robust and sufficient collection of evidence, participant groups were more likely to use the Web to find unique evidence than to they were to use the provided materials. Content knowledge increased, but an issue with teacher conceptions of primary data was identified, as none of the participants chose to use any of their experimental results in their final arguments. The results of this study reinforce multiple calls for science curricula that engage students (including teachers as students) in the manipulation and questioning of authentic data as a means to better understanding complex socioscientific issues and the nature of science.