## 1 Introduction  
Augmented Reality (AR) has been progressively advanced and widely used nowadays in many fields, including that of education. AR blends the real world with virtual reality, as it augments the real environment with digital elements [1] and allows manipulation, exploration, creation, and interaction with virtual artifacts [2]. Due to its nature, AR can easily visualize abstract concepts and phenomena as well as invisible objects [3]. Therefore, AR could provide the learner with a deeper learning experience through active engagement and seamless interaction with the 3D objects. Additionally, the integration of AR applications into the educational process indicates an increase in the learner's performance, motivation, satisfaction, and creativity [4]. As a result, AR could have huge potential, providing new ways of teaching and learning.  
Despite the rising use of AR technology, the research studies that integrate AR into education are relatively few in the field of sciences, such as history [5, 6], physics [7, 8, 9, 10], astronomy [11, 12], chemistry [13, 14], biology [15], mathematics [3, 16], programming/ computational thinking [17], and geography [2, 18, 19]. For example, in the subject of Geography, on the one hand, the traditional way of learning places the learner as an information receiver [19]. On the other hand, a game-based learning approach, which implements learning activities with game principles, such as appropriate and constructive feedback and interactivity, can promote the learner's engagement [20]. Therefore, AR with game-based principles could complement the traditional way where the level of interaction is very low, enhancing the learner's experience, and improving the retention of information [21] as well as the learning outcome [22].  
Taking into account the aforementioned, the current work implements three AR applications in the subject of Geography in the fifth and sixth grades of Greek primary schools. The proposed AR applications include game-based design principles, such as providing meaningful and guided feedback as well as promoting interaction. In addition, an experiment was conducted to evaluate the AR applications. Teachers and pupils of fifth and sixth grades, as well as computer science students, participated in the experiment. They evaluated the AR applications on usability and how game-like they were. Finally, it is worth mentioning, that this study is based on previous research work [10], in which an indicative platform for teaching different subjects in all the classes of primary and secondary school was proposed. Within this context, the proposed three AR applications will extend the current version of the platform by adding a second subject to that of Geography.  
The rest of the paper is organized as follows. In Section 2, a literature review is presented regarding the utilization of AR in education and specifically in the subject of Geography. The architecture of the AR Geography applications along with the analytical description of each of the apps is depicted in Section 3. In Section 4, the pilot experiment along with the procedure and material is presented, and in Section 5, the results are discussed. Finally, Section 6 concludes the paper, and presents the limitations and future work.