In our analyses we have borrowed from Latour’s framework of scientific work as literary inscription as a way to understand students’ use of data as evidence in explanations for a complex problem. Although our analyses are preliminary, one of the major findings of this study is that students’ rhetorical use of evidence in this context has much in common with Latour’s accounts of professional scientific practice (Latour, 1987; Latour & Woolgar, 1986). In particular, students here were largely sensitive to the need to cite data to support their claims, and they commonly used their data rhetorically to support their claims. We also claim that a second contribution of this analysis is to suggest a way to extend recent work examining the structure of students’ arguments (Bell & Linn, 2000; Kelly et al., 1998) by considering the quality of the data students use to back up their claims.