As every conscious activity solution of a mathematical problem is also based on previous experience. But it is not always "mathematical" experience which influences this problem substantially. This contribution is devoted to the study of this phenomenon. It deals first of all with the cases of deformation of solution process of a mathematical problem on the basis of experience from the "real" world for children of age from 7 to 12. In connection with this it asks the following questions: Is it more or less a rare case? In what kind of problems does it occur? Is there any connection between the frequency of occurrence of the mentioned phenomenon and mathematical abilities of the child? What is the role of the child's age here? Which phases of the solution process can be deformed? What follows from all of that for a teacher and the educational process?