A picturebook is usually the first book that the child is encountered with and it has an important role in further experience and understanding of literature. The mathematical picturebook How Leo got to know numbers presents a specific mathematical content (numbers to 10) to students using text and illustrations carefully designed under the supervision of experts involved in the project Math Picturebooks – Artistic and Literary Activities as an Encouragement to Young Learners. In the research a correlation was made among student – teacher - mathematical content – parents – artefact (picturebook) that are present as the vertices of the socio-didactical tetrahedron. The socio-didactical tetrahedron was created by expanding the didactic tetrahedron with the social dimension of mathematics and it is important for a better understanding of the process of mathematical education and the mathematical methodology as a science discipline. The mathematical picturebook was positively accepted by all the participants of the research and also a cooperation between parents and students as well as parents and schools was reached. Both girls and boys were equally interested in the picturebook and the parents considered the mathematical picturebook suitable for bringing mathematics closer to students in school.