Teaching a large class can present real challenges in design, management and standardisation of assessment practices. One of the main dilemmas for university teachers is how to implement effective formative assessment practices with accompanying high-quality feedback consistently over time with large classroom groups. This article reports on how elements of formative practices can be implemented as part of summative assessment in very large undergraduate cohorts (n=1500 in one semester), studying in different modes (on- and off-campus), with multiple markers, and under common cost and time constraints. Design features implemented include the use of exemplars, rubrics and audio feedback. The article draws on the reflections of the leading teacher, and argues that, for summative assessment to benefit learners, it should contain formative assessment elements. The teaching practices utilised in the case study provide some means to resolve the tensions between formative assessment and summative assessment that may be more generally applicable.