Central to teaching is a grand dichotomy: public and private. Children need the protection of privacy to form their own identities: they try out new roles and need to be sheltered from some consequences of these attempts so that they feel confident to keep trying. Forming an identity, however, is also a public concern: the very roles that children try out have been defined by communities. Teachers are given special responsibility to determine public and private for children, but little guidance in making these judgements. Following Habermas, I contend that deciding public and private is especially difficult for teachers, because the bureaucratization of society in general and schooling in particular has eroded distinctions between private and public. I suggest that Habermas's discourse ethics with its typology of pragmatic, ethical and moral discourses each aimed at different goals--and requiring different conditions of communication--can help teachers create common and uncommon worlds for their students. (Contains 2 notes.)