GREEN&STEM mobile application supports outdoor peer-to-peer and collaborative learning. The mobile application provides various tasks to motivate children to apply theoretical knowledge in practice using mobile devices outdoors. For instance, as students approach the park playground, different actions will appear on their smartphones and will lead them (let’s say) to evaluate the slope of the slide. The target groups are students aged 8-16. The application uses gamification for achieving a motivation for STEM-oriented careers and at the same time provids an opportunity to bridge the gap of using modern technologies to support outdoor activities. Hence, children use smartphones to learn outdoor and enjoy nature at the same time. The prototype application is developed in four languages: English, Slovenian, Spanish and Macedonian. It is developed in the frames of the Erasmus+ project Learn GREEN - Оutdoor STEM (https://stem.fis.unm.si/) at the Faculty of information studies in Novo mesto, Slovenia.