There is an extended concern related to renewable energies in South America. Particularly the Uruguayan government is encouraging initiatives in solar, biofuels and eolic wind energy issues. On the other hand, and in a similar manner than in other countries, Uruguay celebrates the “Science and Technology Week”, an activity annually organized, focused on sharing knowledge between scientists and technologists and society. In 2012, this week was devoted to energy and sustainability. In this framework we carried out an interactive activity in five primary school classes with the aim of bringing materials science and solar energy to children between 10 and 12 years old. In the beginning of the activity we asked students to complete a brief survey containing a few questions about materials and energy. This survey allowed us to further the children’s knowledge about these topics. Then, we introduced materials science history relating it with mankind development. From the active participation of children in the activity, we derived to materials applied in solar cells, performing demonstrations with real solar cells and showing their importance for improving our country energetic efficiency while preserving the environment. At the end of each activity students showed great enthusiasm about including alternative energies in their daily life. Furthermore, they realized the importance of materials science, and were capable of understanding the relation between materials and the development of solar cells. We consider the spread of this activity as an excellent way of creating consciousness from an early age, which will help in the achievement of a more sustainable country.