This paper reports the results of the Inf@nziaDigiTales3.6 project on the design, development and evaluation of an augmented reality application to support situated learning experiences in a smart city. The users of the application are primary school children and the case study refers to recognition of road signs as geometric shapes. The objective is to allow children to comprehend the meaning of road signs of a city and to guide them in the recognition of the geometric shapes and colors connected to these signs. The mobile application is based on the paradigm of games and uses a virtual character with the role of intelligent tutor. The results of the evaluation confirm the expected benefits related to the adoption of augmented reality and mobile technologies, mainly in terms of involvement, pleasantness and willingness to repeat the experience. The results show that the re-mediation of augmented reality and the intelligent tutoring system have influenced the memorization processes of figures and colors, as well as of the contents of most of the signals presented. The application has been also deployed on smart glasses and shown in the context of an international event for children and teenagers, the Giffoni Film Festival 2018.