This study characterized and compared the arguments eighth grade mathematics students created while working in technological and non-technological environments. Toulmin's (1958/2003) argumentation model was used to analyze the content and structure of the arguments, including the ways in which the students used the tools (technological and nontechnological). Students in both classes were less likely to make their reasoning explicit when using tools, technological or non-technological, which may be related to the task on which the students were working and the use of the tools as a visual referent. [For the complete proceedings, see ED585874.]