The widespread use of mobile devices is leading towards their adoption in the learning process, even if some pedagogical challenges are still not fully addressed when integrating mobile-assisted activities into regular curricula activities. In this paper, we first define some guidelines to design a general, tailorable, and platform-independent mobile learning system. Second, we present the aCME system, a mobile infrastructure, developed by adhering to the defined guidelines, to provide a general-purpose system, easy to start up with and friendly to user, and finally, tailorable, i.e., that can be easily adapted to the needs of different learning environments. The aCME system has been implemented as a Web-based architecture, to provide content and functionalities for different contexts, accessible from any location and by using any communication device. Finally, we describe a tool, deployed into aCME, that allows responding to quiz-based questionnaires during learning activities. A preliminary evaluation was performed to analyze usability and user satisfaction when interacting with the system we developed. The paper is concluded with some comments and future research directions.