Mobile learning whose definition unfolds in the learning process supported by the use of mobile devices is a field of study that has been drawing the attention of several multidisciplinary studies. This research has as hypothesis that the continuous study with the support of a mobile application of foreign language teaching, using a smartphone, increases the possibility of the proficiency, since it allows the study in multi-contextual locations, facilitating the frequency and access to the content to the users. From the Human-Computer Interaction area and using User-Centered Design techniques, this research had as objective the investigation of the factors that contribute to the continuous construction of knowledge of the users of a mobile application of foreign language teaching. Three approaches guided the research: the first was a historical-evolutionary review of distance learning, to understand how pedagogical processes are converging to mobile technologies. The second was a brief analysis of the information architecture and the user experience to delimit the operation of the main language teaching applications of the Brazilian market, like Duolingo, and lastly Usability Tests and Diary Studies for collecting data that confronts the hypothesis. The research results indicate that Duolingo presents, in general, good usability properties. These properties reinforce that the hypothesis is valid when the motivating factors of the participants show the tenuous balance between daily routine, partial proficiency in the language studied and clear learning objectives.