To prepare their students to navigate online information about current issues, teachers must be able to critically read a range of diverse and complex data visualizations. This study presents findings from task-based interviews with 25 social studies teachers on their instructional beliefs about the use of diverse data visualization types. In the interviews, teachers ranked two sets of data visualizations for their usefulness in teaching. One set was drawn from textbooks and the other from online media in order to highlight the challenges of visual complexity. The teachers' rationales for their choices showed that they primarily think of data visualizations as unproblematic and discrete information instead of as sources of evidence that need to be critically evaluated. The results contribute to our understanding of teachers' thinking about the uses of visual information and suggest implications for preparing teachers to assist students to critically evaluate online visual information.