The article reviews the process of developing training content of the on-line course on the project method for Mathematics teachers teaching at higher technical universities. The study presents the first stage in developing training materials and a model for the structure of the on-line course «Project Method in Teaching Higher Mathematics», which is in open access on the «Higher School Mathematics Teacher» educational platform. The original version of the course was designed on the basis of the findings of a survey among the Mathematics professors. It helped to find out the level of their awareness about using the project method in training engineering students. It also gave the authors of this paper good reason to recommend the on-line course for the professional development of Mathematics teachers. After uploading to on the platform the original version of the course, we managed to organize a discussion of the proposed content, structure and modes for submitting the course materials on the forum. The article discusses the process of modifying the course components, improving training material during the forum discussion. The analysis of the feedbacks from the course users on the forum, confirmed that the variety of submitted forms of course materials and the proposed topics satisfied the preferences of the course users with regard to the perception and awareness of the educational information.