In this paper we describe and give arguments to specific work with students, future primary school teachers in the learning process of the harmonic instrument, which is the toughest task of musical literacy of students through vocal instrumental teaching. In response to long-term follow-up reactions of students during the teaching process, a special method of learning the accordion has been devised, adapted from one by the elemental demands of musical literacy of students the University of Belgrade, in the given time frame of only two semesters for teaching, and on the other side of the given music abilities of students as a group. In this paper we study the analysis of the situation, problems and tasks in learning a harmonic musical instruments, primarily the accordion and then the piano, that this type of education stand in relation to the classical training (in the field of organization and implementation), placing them in order specifics. It is also a concise methodical approach to explaining the role and importance of the C-major scale in the initial learning the accordion, scientific and illustrated by examples from music literature. The aim of this paper is to show the methodological value of the specially designed vocal and instrumental instruction for students, future primary school teachers and to define methods of successful fast learning of the majority harmonic musical instrument - group four-tact learning how to play an accordion, and forming am model of the right observing and leading a teaching process.