This classroom discourse study examines how curriculum becomes a resource for identity performance in one ESL classroom. Conceptualizing identity as performance, I adopt a small stories approach to analyze how one routinized vocabulary instructional activity was appropriated by classroom participants to perform identities and construct the classroom moral order. Through analyses of two excerpts of classroom talk, I show that the ESL teacher narrated her story into teaching as an instructional example and performed a dominating teacher identity rhetorically portrayed in a morally positive light. A Taiwanese immigrant boy appropriated the language practice for displaying a funny, nonlearner masculinity. His identity-displaying narrative, however, ran counter to the moral expectation of being a "good learner" embedded in this language activity, leading to his social identification as a problem student. This analysis illustrates that the identity categories in the language curriculum provided linguistic resources for the classroom participants to perform identities that worked to perpetuate or challenge dominant discourses of being. The process of teaching and learning is deeply intertwined with identity negotiation and moral positioning. This analysis also illuminates the theoretical and methodological affordances of a small stories approach to examine the emergence of identities in language classroom discourse.