One of the demands in Mathematics curricula applied in Portugal is concerned with the development of more positive attitudes regarding Mathematics. An innovative task developed in an open space was able to change students' attitudes, as well as their horizontal and vertical interactions. This activity was part of the project Interaction and Knowledge whose main goal is to study and promote collaborative work in Mathematics classes. With this methodology pupils had a closer contact with a content that is usually described as difficult and hardly motivating. Due to the nature of the task and collaborative work, students used everyday knowledge in their answers, promoting an appropriation of Mathematical knowledge.