Introduction of Philosophy plays a fundamental role in teenagers' education in Portugal. Students should enjoy a culture in and for citizenship. So, it is urgent to implement classroom practices in which students must be the main resource in the teaching-learning process. To achieve this goal we elaborated an instrument to evaluate essential skills to think philosophically. This instrument allowed for the elaboration of the dyads in the beginning of the school year. We are going to illustrate some of these skills and the tasks that evaluate them. To implement collaborative work as a daily practice teachers need to know pupils' competences better in order to choose peers and elaborate academic tasks that facilitate both pupils' achievement and their socio-cognitive and affective development.