This paper focuses on the study of oral speech in the university classroom, using the principles of Systemic Functional Linguistics (Halliday, 1994). Following on Walter Ong (1993), we discuss on the possibilities offered by oral communication practices to guide the construction of university student's own speech. Based on Systemic Functional Linguistics and the Mood System, specific to the interpersonal function of language, and using evidence from previous researches, (Muñoz Dagua, 2009; Muñoz Dagua, 2010; Cisneros-Estupiñán, Rojas y Olave, 2005), we justify the use of the Appraisal Theory (Martin, 2000). This theory is related to the evaluation of grammatical lexical resources, attitude, commitment and gradation in specific contexts as a methodological procedure to identify problems in classroom oral interactions, and suggest mechanisms to improve academic discursive practices.