"In the presentation, a study on the impact of the familial socialisation on mathematics learning will be described. The aim of the study is the development of theoretical insights in the functioning of familial interactions for the formation of children's mathematical thinking. The idea of Mathematical Learning Support System is examined in order to shed light on how family members can be supportive or helpful for the mathematics learning process of a child. In this sense the negotiation of meaning during the block play is observed and identified by using interaction analysis. The result demonstrates that a block play with family members takes place as a social act for a child and each family member provides different learning opportunities to the child, who is exposed to learning about giving, receiving, sharing, and expressing her ideas and feelings. On the basis of this result, it can be concluded that through a block play with family members, a child gets an opportunity to think, to talk, to learn, and to be 'educated' in mathematics and in cognitive, social-emotional competences as well."