There is a discussion on the potential of augmented reality (AR), mobile technologies to enhance learning. This article presents: 1) the EduPARK project's first cycle of design-based research for the development of a mobile AR game-like app that aims to promote learning in an urban park, and 2) an experience of students using it in loco. The focus is the students' perceptions regarding the usability and functionality of the app. Data collection involved focus groups, questionnaires and app usage information. Data was submitted to content analysis and descriptive statistics. Results revealed an excellent usability of the EduPARK app, with an average system usability scale of 85.6. Overall, students reported that the app was enjoyable, easy to use and promoted learning; however, improvements and more evaluation experiences are needed to better understand mobile AR game-like learning in urban parks.