This article considers the issue of on-line training of Master students, majoring in Mathematics (Speciality code in Ukrainian educational system "014.04 Secondary Education. Mathematics") and preparing them for teaching at University. The research papers and resources, focusing on the vocational bent of on-line training of undergraduate students majoring in Mathematics have been analyzed in this paper. The present paper describes designing the structure and components for the on-line course "Methods for Teaching Mathematics to Students at Technical Universities", which is in open access on the educational platform "Higher School Mathematics Teacher". This article presents the analysis of the survey results, in which 107 students in their first and second year of studying took part, which allowed defining the content of the course. The model is presented as a polyhedron, vertices, faces and edges of which show structural elements of the model and relations between them. The paper also introduces the analysis of the internship syllabi at Ukrainian universities and aims at defining the criteria for assessing learning performance of the on-line course users. It also considers the impact of the course on the efficiency of training 112 Master students in their second year of study, when they do their assistant internship at technical universities. The qualitative and quantitative analysis of the results of the experiment proved the efficiency of introducing the course into the process of practical training of Master students. The interns who joined the course, showed a better understanding of how to motivate students when teaching Mathematics to them. They also showed better results in applying active learning tools and techniques for teaching Mathematics, as well as in managing the audience through information technologies and communication strategies.