This study examines the performance of dietitians-in-training on developing a diet plan for a diabetic patient either independently or after peer discussion. Participants (n = 58) from an undergraduate program in food and nutrition were divided into two groups based on their prior knowledge before being randomly assigned into three conditions: (1) peer discussion with just-in-time information (JIT information), (2) peer discussion without JIT information), and (3) independent performers. The learners' performance in the three conditions was analyzed. The results presented here describe the role of prior knowledge and JIT information across the conditions and the interaction of the two factors as well as the instructional implications of the findings.