During teacher preparation programmes, pre-service teachers need to reflect meaningfully on their classroom experiences. However, some pre-service teachers tend to provide narrative accounts of classroom events and interactions. Mentors and assessors urge them to "probe more deeply" but give little guidance about what this entails. This study reports on an intervention in which reflection guidelines were changed after noticing how guidelines asked questions that limited professional learning. The revised set of guidelines prompted preservice teachers to make iterative links between the theoretical insights gleaned from coursework and their experiential learning in classroom settings. The Semantics dimension from Legitimation Code Theory is used to compare the reflections written in response to the original and revised guidelines. Using the revised guidelines, two thirds of participants drew more intentionally on theoretical insights to interpret and explain their classroom experiences. The article concludes by suggesting several conditions for enabling pre-service teachers to write "deeper" reflections that are both theoretically informed and contextually responsive. These conditions include access to relevant concepts, guidelines that make expectations visible and access to a language of practice for providing feedback about what "probing more deeply" looks like. I argue that the concepts from Legitimation Code Theory offer such a language.