Written as a letter to a first-year teacher, the author--acting as a mentor, veteran teacher--critically conceptualizes the hidden curriculum using the work of Jackson (1968), Anyon (1980), and others in order to historicize the term for their newest colleague. Following an initial introduction to the hidden curriculum, the author draws on personal anecdotes from their experiences in two urban elementary schools in the Southern U.S. In doing so, the author brings to life the "qualities" of the hidden curriculum as they continue to exist in today's classrooms across socioeconomic and cultural settings. To conclude, the author provides their first-year colleague a set of questions to consider as they learn to see the hidden curriculum in their own classroom and practice. The friendly-letter format of this article offers an innovative way for teacher educators and researchers to engage prospective and in-service teachers in critical conversations about the concept of the hidden curriculum.