This study enacted and supported a scaffolding process to improve preservice teachers' (PSTs') assessment literacy as they experienced school placement. It is crucial to create opportunities that enhance PSTs' understanding of assessment literacy, helping them to reconsider conceptions previously developed as school students (socialisation experiences) and to gain an appreciation for the benefits assessment affords students in their learning. Assessment literate teachers can enact appropriate assessment practices that can improve students' learning and the teaching-learning process while providing opportunities for students to regulate their learning. Eight physical education PSTs working with the same university supervisor took part in the study. Data were collected through individual and focus group interviews, post-seminar reflections and testimonial surveys, researcher's field notes, and PSTs' school placement reports. This study highlighted that supportive, practical and critical participatory approaches are crucial to encourage PSTs to question and change their assessment conceptions, and to improve their assessment literacy. Results also showed that, despite struggling to avoid practicing what they experienced as school students (i.e. socialisation experiences), PSTs can alter their assessment understanding and practices to incorporate assessment for learning principles. Teacher educators are encouraged to consider how they can best acknowledge and address the pre-conceived assessment conceptions PSTs bring into these programmes.