This article discusses the process of scaffolding of two different contexts of interaction in online courses. The corpus is composed of online registration of English classes and Biochemistry classes offered on the Internet through the use of chat. This article aims at verifying which are the differences and the similarities between those real contexts of communication, especially how students and teachers produce knowledge in those environments. The analysis is based on the Socio Cultural Theory and the Communicative Approach. The results show particularities in the scaffolding processes and emphasizes that the most important recurrent categories do not represent the real online interaction that occurs in an online pedagogical chat room