Several studies have pointed out difficulties of various types encountered by students in both secondary and high schools to acquire the exact meaning of the integral and to master the ability to invest it correctly in different domains. This contribution attempts to explore the effectiveness of some cognitive activities engaged in teaching integrals on the achievement of the objectives targeted in secondary school curriculum. For this purpose, a cognitivist analysis of the program is performed by focusing on the implementation of the changes of frames and the conversion of registers of semiotic representation during the treatment of this notion. To explore the effectiveness of these cognitive activities on learning the integrals, a sample of secondary school students were tested. It emerges from this study that the quality of learning integrals of a real valued function and the formation of correct conceptions on this notion are highly correlated to the investment of this concept in various frames and different semiotic registers. In fact, many of the students tested were unable to perform certain algebraic tasks or to interpret correctly some integrals in familiar situations.