In early 2020, Initial Teacher Education providers were forced to reimagine many long-established practices due to pandemic restrictions. One post-primary concurrent Initial Teacher Education programme in the Republic of Ireland responded by conceptualising and developing an initiative to engage pre-service teachers in an authentic assessment task through the preparation of a classroom-based assessment from the perspective of the pupil. They then engaged in peer review and peer feedback on these classroom-based assessments and partook in a Subject Learning and Assessment Review meeting. This required the professional development of assessment literacies on the part of pre-service teachers, as well as disturbing their personal assessment beliefs at a cognitive and affective level. This paper finds that the collaborative assignment experience challenged pre-service teachers’ previous conceptions about the purposes of assessment while providing them with insight and preparation for formative assessment processes in use throughout Irish post-primary schools.