This study is concerned with the formal assessment of a Distance Learning Environment (DLE) created to deliver a course on UML sequence diagrams to university-level students, divided into control and treatment groups. An ad-hoc DLE was constructed to deliver instruction to the treatment group, while the control group was taught in a traditional face-to-face way. The main point of concern is whether a DLE can be as effective for the treatment group, as the face-to-face lecture is for the control group, in terms of gaining mastery on the domain. So, a controlled experiment was organized and executed, in order to measure the participants' performance in both groups. The results have shown no statistically significant difference for both groups of students. So, it can be argued that in the context of this experiment and by following a DLE-design close enough to the traditional face-to-face approach, one can obtain equally good results using distance learning as with the traditional system. However, a number of concerns remain and more work is needed to generalize the results of this work on other domains.