Lesson observation is frequently used in teacher induction programmes to support newly-qualified teachers in their reflection and classroom enquiry. This article uses an elaboration of Peirce's abduction to illustrate how the post-observation conversation supports a teacher's reflection on her teaching, and in particular, her teaching of language to young children. It shows that abduction involves an expert-like intuition, where the interaction and co-enquiry with the advisor was crucial. The analytical framework used is based on six modes of abductive reasoning or inference that deal with potential or possibility, three modes of induction dealing with actuality, and one mode of deduction focusing on rules and regulations. In a context of lifelong learning, with emphasis on teacher learning across the professional lifespan, the article shows how newly-qualified teachers can be supported in using abductive reasoning and engage in worthwhile classroom enquiry. The article contributes to edusemiotics, a recently developed direction in educational theory that explores the philosophical specifics of semiotics in educational contexts.