2024 Yes Protocol for the Open Sky School: a two‑arm clustered randomized controlled trial to test the effectiveness of a nature‑based intervention on mental health of elementary school children https://doi.org/10.1186/s12889-023-15033-y Loose, Tianna North America Experimental Students Elementary (K-5) Green space Stress/Anxiety school-based intervention Mental health children randomized controlled trial Nature outdoor education elementary-school children greenspace This RCT protocol tests a 12-week outdoor education program in Québec elementary schools. Children spend 2 hours weekly in green space. Primary outcome is mental health symptoms; aims to inform scalable nature-based school interventions. 2023