This paper is concerned with a new type of real-time feedback system in a classroom based on the text data collected from the audience. After reviewing two traditional approaches to real-time feedback; the Clicker Approach and the Forum Approach, it will be suggested that either of them is insufficient as a tool to motivate the learners in a case of presentation course. Instead, we propose two systems on the basis of text-mining technique to compensate for these insuffiencies. The first is a "Keyword and Frequency" system and the other is "Mind-mapping" system. In this paper, we describe the details of the systems. By being presented the keywords and data on frequency, the presenters can easily understand about the general feedback tendencies. In addition, the mind-map picture gives the presenters the opportunities of promoting a new awareness, various kinds of discoveries, and a deeper reflection about their works. Totally, our system can be incorporated into Learning Management System (LMS), and it has a large potential for further use in a distant learning environment to capture an overall reaction from the audience all over the world.