We illustrate a method, which is modeled on "breaching experiments," for studying tacit norms that govern classroom interaction around particular mathematical content. Specifically, this study explores norms that govern teachers' expectations for the doing of word problems in school algebra. Teacher study groups discussed representations of classroom interactions in which the class is doing a word problem and a student solves the word problem without writing an equation. Toulmin's scheme for everyday argumentation was adapted to analyze the study group talk. This analysis suggests that, for this sample, word problem norms are in flux; it may no longer be necessary for a student to state and solve an equation to do an algebra word problem. We propose that further research will have to determine whether the emerging change in these norms is attributable to policy initiatives in local contexts or whether it represents a larger cultural shift in conceptions of algebraic symbols. (Contains 12 figures and 20 footnotes.)