To resolve the teaching problems in Materials Engineering major, with students from the local university with low interest in learning and studying, this research is based on stimulating students' curiosity. Unlike the traditional sequence of teaching materials in which crystalline and atomic models are studied from the literature to later arrive at a phase diagram; this experience begins directly in the laboratory with students doing cooling curves for the two alloys. After this, students make metallographic samples with the cooling obtained. This experience results in a research activity by which students observe a phenomenon, measure values, verify changes and transform two metals in a number of phases before they study the theory. In this way, students understand the theoretical explanation as a necessary element to further delve into the scientific activity as opposed to pre-established knowledge that is imposed on them. Cognitive processes seem to be highly activated when curiosity intervenes as motivational energy in the classroom.