Mathematics constitutes ideal material for exercising the art of learning and thinking. For this it is necessary that the classroom has a stimulating atmosphere which requires determined attitudes and beliefs. The book combines theory and practice and responds to questions such as these: to think in the mathematics class? on what does the knowledge of solving problems really consist of? what are the beliefs and which are the most common ones among the students? how to diagnose, evaluate and, in some cases to modify, the systems of beliefs of the pupil?).