The literature on teaching controversial issues offers a framework to help teachers make appropriate judgments about which topics are worthy of deliberation and what information is reasonable to consider in a classroom. Wayne Journell describes four criteria for evaluating the openness of issues, explains why the behavioral criterion is neither feasible or desirable, unpacks the three criteria that the literature has identified as reasonable (the epistemic criterion, the political criterion, and the politically authentic criterion), and then discusses how teachers can make decisions when the criteria disagree.