In this paper we offer a significant development of Baldry and Thibault's (2006) notion of a ‘meaning-making trajectory’ to explore the collective, and often improvisational, interactional processes of meaning making in classroom dialogue. We report a sociocultural discourse analysis (Mercer, 2004) of a series of history lessons with a class of 6–7 year-old children, which utilises the notion of ‘meaning potential’: to highlight the valuable distinction and flexible interplay between a teacher's intended meaning-making trajectory, and the meaning-making trajectories that are instantiated in interaction with pupils through dialogic interaction. We argue that where disparities are identified, often through pupils’ unexpected questions or contributions, there can be valuable teaching-and-learning opportunities for collaboratively constructing and appropriating common knowledge.