The mathematical prove is, despite restricted use in teaching, essential for the logical and structured thinking of adolescents.This work is supposed to deal with the topic of prove and its realisation in mathematical class. The first part attempts to specify and suggest the tasks of argumentation in school. Furthermore, examples for appropriate teaching methods are shown. This investigation discusses the Austrian curriculum and several international studies in terms of mathematical prove. In addition, two schoolbooks are introduced and reviewed about this topic. Concerning the empirical part, questionnaires about the mathematical prove and its argumentation were distributed to students and their class teachers in mathematics. 97 students who had been attending the 11th and 12th level of education from two Styrian grammar schools focussing on natural sciences were interviewed. They answered questions about demographics respective school and mathematics. Furthermore, the students were asked to accomplish concrete proves and to differentiate statements between their meaning. In this study, a general interest of students for mathematical argumentation was recognised. Besides, students having weaker school marks, private lessons and/or less mathematical interest revealed a lower quality of reasoning regarding vocabulary and formal criteria. In addition, almost all lecturers determined that there is a lack of teaching time for the procurement of mathematical proves.This investigation, finally, encourages the importance and practical implementations of mathematical prove in school teaching. Thus, there should be a larger temporal scale for its teaching.