Learning Analytic (LA) systems are aimed at supporting teachers in understanding the learning process by analyzing the information and the interaction of students with computer systems. In the case of a project-based learning process there is a need of introducing measure the student' activity as acquired via multiple modalities and then processed. The acquisition and processing needs to take into account the specificities of the learning context and deployment at schools, in particular in terms of system architecture. The paper proposes an architecture for the acquisition and processing of data for project-based LA designed to be interoperable and scalable. System design, details of the solutions and brief examples of acquired data are presented.