ProSys (Project-based system) is a web-based adaptive learning environment designed to support traditional classroom-based teaching as a supplementary resource. Projects are used as a building element in organizing learners' study; learners select a topic and then the system proposes them to start working on a project in order to achieve a set of learning goals.
The design rational of ProSys is based on constructivist theories combining project-based learning (Thomas, 2000) with case-based learning theories (Bennett, Harper & Hedberg, 2002). Project-based learning focuses on relatively long-term, integrated units of instruction where learners work on complex projects consisting of multiple cases. A critical characteristic of meaningful learning is mindful activity and in such activities the lack of experience is especially critical (Jonassen, 1999). Thus, following Jonassen (1999), the inclusion of realistic cases in a constructivist learning environment provides learners with access to experiences that they have not previously encountered. A case-based approach, which combines engagement with meaningful real-world tasks and expert coaching, can provide deeper insights into processes and practices (Jonassen et al., 1993).
Four discriminative characteristics of ProSys are:

a. the use of projects as authentic activities that learners undertake; learners select a topic and then they start working on a project to accomplish specific learning goals,

b. the adoption of a specific learning cycle that proposes learners to follow a sequence of activities in order to deal with the project and progressively deepen their understanding. Through the different stages of the cycle multiple opportunities are offered to learners to articulate the reasons of their actions, explain the strategies they use, see and comment on their peers' ideas, arguments and strategies, aiming at promoting participation,

c. the provision of educational content consisting of multiple cases that deal with different perspectives of the project and offer a means to contextualise learning and assess their knowledge in a way that connects content and action, and the provision of adaptive navigation support through the content based on the learner's knowledge level and progress,
the externalization of the learner model that the system maintains during the interaction aiming to promote reflection in learners about their knowledge and learning.

d. the externalization of the learner model that the system maintains during the interaction aiming to promote reflection in learners about their knowledge and learning.