Open education has revolutionized the educational environment. Massive open online courses have become the main showcase for open educational resources, but the competition to establish a position in this movement has led to the rapid publication of many courses of arguable quality. This paper presents and analyzes the process of creating a small private online course that meets the requirements to be offered as a massive course. The starting point was an online higher education course that had previously been published as OpenCourseWare. In this paper, data were examined from 112 students enrolled in four different academic years, during which changes were progressively incorporated to transform the traditional course to an open course. The results show an improvement in students' perceptions of resources and assessments and in their overall satisfaction. New assessment tools were developed and validated, without affecting the academic results. The process had positive effects on the instructional design of the final course, but some risks were identified when the course was adapted as a massive course. The final course provides useful input for future developments and a more effective student-focused methodology.