DIY TANGRAM PROJECT This STEAM-based project was carried out in a 4th year of secondary education (4º ESO B y C) academic mathematics class through cooperative learning groups. The main goal was the geometric construction of a tangram using a variety of materials, combining hands-on learning with mathematical reasoning. Students worked collaboratively to design and build their own tangram pieces, applying concepts of geometry such as shapes, angles, and proportionality. Once constructed, the tangram became a tool for exploring similarity between figures. Learners solved different problems involving scale, ratios, and geometric relationships among the pieces, fostering analytical thinking and problem-solving skills. The project culminated in an oral presentation in English, where each group introduced different hands-on games and activities using their tangram sets. Throughout the project, students developed key competences and skills, including mathematical reasoning, spatial awa...