The aim with this paper is to present research about teaching in preschool and the meaning of education in the preschool context within the perspective of quality. More specific the research focus on teaching mathematics and didactical considerations.Teaching mathematics always consists of several components with teacher, children and the mathematical content as three major parts. One of these basic components includes preschool teachers' intentions, choices and actions in which the goal is to create opportunities for children's learning in mathematics. Another component is the children, with their own experiences, intentions and their own choices. A third component is the mathematical content of the teaching situation (Brousseau, 1997). Play is a keyconcept in mathematical activities (Bishop, 1992) and in teaching of a mathematical content (Brousseau, 1997).The research focus is on didactic situations and more specifically the social interaction in teaching so-called didactic contract (Brousseau, 1997). Didactic contract can be understood as the dilemma between the educational goals and the participants’ intentions. A case study illustrates didactic situations in one Swedish preschool.Permissions has been gathered from the parents. The ethical rules for researcher in Sweden have been followed.The findings show the teachers use of play aspects in didactic situations expands the learning opportunities. The didactic contract in teaching give learning opportunities for children. Preschool teachers use of play in didactic situations make the teacher's aware of the mathematical and didactic considerations in relation to context and thereby improve the teaching of mathematical content.