The academia-industry cooperative lectures on project management was begun starting from the fiscal year 2012 at Hiroshima City University and Hiroshima Shudo University. In the lecture, two campuses and the office of the Japan chapter of the Project Management Institute (PMIJ) at Tokyo are connected via a teleconference system. Teachers give their talk sometimes from one campus and sometimes from the office of the PMIJ. For this case of distance learning, a web service providing teleconference facility was adopted and, in order to compensate for the thin communication bandwidth, a messaging service of a social networking system (SNS) was used concurrently. This paper reports several results of analyses of the effects of messaging via a sub-channel, based on an investigation of the chat transcripts.