Teacher training for the implementation of specialized training courses is one of the key areas in the formation of professional competencies. In addition, the program requirement for teaching mathematics is to develop in students correct ideas about the nature of mathematics and the reflection of phenomena and processes of the real world by it. This can be achieved through the study of elective courses of economic and mathematical content. The article describes a pedagogical experiment within the framework of training students pursuing bachelor's degree in "Teacher Education" to design and implement elective courses focused on economic and mathematical content. Analysis of the literature on training future math teachers to create and run elective courses and interviews and tests made by students and teachers show that there are difficulties in identifying specifics, structure and content of such courses. There are also problems with using active teaching methods and the method of mathematical modeling. To overcome these difficulties, a special course for teachers has been created and put into practice. The experimental data obtained at significance level less than 5% confirm the hypothesis of the study about the efficiency of forming future math teachers' readiness to design and implement elective courses focused on economic and mathematical content by the developed technique.