Mobile computing devices facilitate mobility and face-to-face interaction when compared with desktop computing, but lacks of the computing power of the latter. Therefore, a key aspect to ensure success of a learning supporting mobile application is whether mobility is really needed for the activity it supports and if mobile devices do really represent an added value compared with the same application implemented on non-mobile devices. In this work we first analyze the best known collaborative learning practices trying to find out which are the real need for mobility and face-to-face interaction and then design and develop an application called MC-Supporter implementing a, problem-based, collaborative learning application based on these requirements.