This paper analyses the reasons underlying children's difficulties when solving realistic wor(l)d problems in the mathematics class. In order to do so, first, international studies on these difficulties are reported. Second, we describe how characteristics of the current textbooks and classroom interaction led children to learn that mathematical problems must be solved by using only mathematical information and procedures, and not by attending to relevant real-world aspects of these problems, and how this learning process moves away the mathematics from the school from real life. Third, an intervention study that showed how the classroom practice and culture can be successfully modified is described. Finally, some comments about the limits of these ideas are made.