This paper reports the development of innovative assessment sessions within two core technical courses in Civil Engineering at the University of Queensland. Peer Assessment Learning Sessions (PALS) facilitate a student's peer assessment of a colleague's problem-based learning assignment or tutorial within a "traditional" whole-class setting, under guidance from the lecturer. The assessment is carried out against worked solutions, with a template marking scheme. Following the class, submissions are reviewed by the lecturer and marks moderated if required. In combination, the review and the PALS provide very clear indication where the class or individuals have misconceptions, and where knowledge is below required criteria. This enables the lecturer to provide an accurate synthesis of these points to the class. Students obtain summative feedback, individual formative feedback and whole-class formative feedback within a few days of submission. This significantly improves student's self-reflection and their review of class material. Feedback is very positive and demonstrated here through the presentation of anonymous survey results. PALS address the challenge of providing frequent, efficient and timely assessment for large classes of 100-200+students while simultaneously enabling and providing high quality formative feedback. (Contains 1 table and 8 figures.)