This study investigated how high school students evaluated online information on social and political topics. Eighteen juniors and seniors, at a school that attempts to leverage technology to personalize learning, thought aloud as they completed online reasoning tasks. Three themes emerged from analyses of think-aloud data. First, students assembled ad hoc lists of surface features (e.g., a website's layout or top-level domain) that they used to render decisions about whether content was trustworthy. Next, they judged the usability of an article as a way to decide whether it was reliable. Finally, they interpreted the presence of data as conferring credibility on online posts, regardless of the quality of the source. These students spent a great deal of the school day in front of computers, yet this study suggests that students relied on evaluation tactics best suited for vetted print information--not the open web.