This book is the result of academic research carried out in 2009, which aimed to analyse the situation of error in the teaching-learning process, based on the conceptions of primary school science teachers, based on the epistemologies of Gaston Bachelard and Jean Piaget. In this work, we adopted a concept of error based on these two epistemologies, which have a sense of cognitive growth, achieving, respectively, both the progress of science and of the human intellect. The research used the hermeneutic-interpretive method to appropriate the theoretical references and a qualitative approach to collect and analyse the data. At the end of the study, we were able to conclude that while teachers understand the importance of error in the process of building knowledge, they still maintain a traditional practice in relation to this element of knowledge building.