Many classroom units and lessons are now organized around engaging students in developing claims and evidence. An aspect of teachers' work that is understudied is how teachers manage the complexity inherent in navigating between claims and empirical data. In other words, what do teachers do when students do not see what they are "supposed to" see or when they make sense of observations in unexpected ways? We contend that such complexity is inherent to the scientific endeavor, and that engaging with it is central to doing science. Therefore, the moves that science teachers make in this context have important consequences for students' conceptual and epistemic understandings. We apply an "epistemic levels" coding scheme to three classroom episodes in order to better understand the complexity of classroom evidence construction and to develop a description of strategies that teachers might enact to manage this complexity. We then discuss the implications of these strategies for how students are positioned to engage in scientific knowledge construction.