This is a practical educational guide developed within the MULTIPLIERS project to help teachers organize field-based learning activities using marteloscopes. The document introduces marteloscopes as outdoor forest classrooms where students can explore forest ecosystem services, biodiversity, sustainable forest management, and the trade-offs between ecological and economic objectives. Using the I+ Trainer digital application, students analyze individual trees, investigate habitat and timber values, and role-play as forest managers or conservation practitioners to make evidence-based management decisions. The guide provides step-by-step instructions for planning visits, engaging experts, facilitating discussions, and encouraging students to act as knowledge multipliers, making it a valuable resource for environmental education and forest literacy. [Martelosco...-materials | PDF]