The article addresses the issue of implementing the usability principles of educational internet resources. The paper debates the latest researches on the question concerning the search for the factors that influence the results of online education. The analysis, which we carried out, allowed us to focus on such known six criteria of usability design as Information Quality, System Navigation, System Learnability, Visual Design, Instructional Assessment, and System Interactivity and suggest the existence of the seventh criterion named Responsiveness. The research considers the principles of usability implementation following the example of the open platform of online education “Higher School Mathematics Teacher”. The answers given by the respondents during the survey allowed defining the direction of implementing the usability criteria on the platform. The article discusses the criteria implementation while developing online courses on the platform.