The goal of this study was to increase our understanding of the learning-oriented verbal interactions taking place between students during the problem-based learning (PBL) cycle. The verbal interactions of one PBL group of five students throughout an entire PBL cycle were recorded in this data-intensive case study. The verbatim transcript consisting of more than 1,000 utterances was analyzed to investigate whether and how PBL stimulates students towards constructive, self-directed and collaborative learning. Our results demonstrate the occurrence of all above-mentioned learning activities, with 53.3% of episodes being collaborative, 27.2% self-directed and 15.7% constructive.