Microplastics are a dramatic emerging problem for human health and ecosystems. Since we cannot pollute to quantify pollution, during the Green Chemistry and Outreach course, taught to a fifth-grade class at ITT Montani in Fermo, we evaluated the impact and effectiveness of analytical strategies currently used to monitor microplastics in sand. We worked to substantially improve them using CLIL and Inquiry-Based Learning methodology. The citizen science campaign was made possible by cooperation with the non-governmental organization Venice Lagoon Plastic Free, which coordinated the field sampling campaigns and funded them entirely through the MICRO 1.0 and 2.0 projects. Finally, we engaged in outreach campaigns as part of the EU Ocean Mission activities.