The "Green Schoolyard Evaluation Tool" (GSET) was applied to assess 34 schoolyards in Rotterdam as part of the COOLSCHOOLS WP4 project. The evaluation focused on key features including greenery, design, play and learning opportunities, water elements, and habitats for animals. Most schoolyards featured diverse greenery and elements supporting active play, such as areas for climbing and natural materials. However, water elements were present in only half of the schoolyards, and while animal habitats were generally under-recognized, over 20 schools included features like messy natural spaces and branch fences. The findings offer insight into the multifunctionality and ecological potential of urban schoolyards.