Introduction: Portfolios scaffold reflection on experience so students can plan their learning. To elicit reflection, the learning experiences documented in portfolios must be meaningful. To understand what experiences first- and second-year medical students find meaningful, we studied the patterns in the artefacts chosen for portfolios and their associated written reflections.

Methods: This explanatory mixed methods study of a longitudinal dataset of 835 artefacts from 37 medical student’ portfolios, identified patterns in artefact types over time. Mixed model logistic regression analysis identified time, student and curriculum factors associated with inclusion of the most common types of artefacts. Thematic analysis of participants’ reflections about their artefacts provided insight into their choices. Interpretation of the integrated findings was informed by Transformative Learning (TL) theory.

Results: Artefact choices changed over time, influenced by curriculum changes and personal factors. In first year, the most common types of artefacts were Problem Based Learning mechanism diagrams and group photos representing classwork; in second year written assignments and ‘selfies’ representing social and clinical activities. Themes in the written reflections were Landmarks and Progress, Struggles and Strategies, Connection and Collaboration, and Joyful Memories for Balance. Coursework artefacts and photographic self-portraits represented all levels of transformative learning from across the curriculum.

Conclusions: Medical students chose artefacts to represent challenging and/or landmark experiences, balanced by experiences that were joyful or fostered peer connection. Novelty influenced choice. To maximise learning students should draw from all experiences, to promote supported reflection with an advisor. Tasks should be timed to coincide with the introduction of new challenges.