It is widely known that university students have serious difficulties in writing academic essays. Our analysis revealed that there are two sources of the difficulties concerning the argument structure and problem formulation. Students do not understand that academic essays in the field of empirical sciences have a particular logical structure whose components are claim, data, warrant, backing, rebuttal, and qualifier as Toulmin (1958) revealed. As to the problem formulation, the lack of the content knowledge prevents students from evaluating the relevance, significance, and feasibility of problems. In order to develop students' writing skill, we designed a collaborative learning environment where students actively interact with their peers online as well as offline. We reported the effects of two collaborative activities, the peer reviewing and Jigsaw learning. The peer review activities enhanced students' recognition of the need for the argument structure and advanced the levels of students' essays. The analysis of the discourse in the Jigsaw learning revealed that active Jigsaw sessions involving explanatory activities contributed to the better problem formulation.