## 3 Mobile Devices and Augmented Reality in Education  
In distance learning environments, it has been possible to notice several deficits in the used education model, especially in practical subjects [5; 48]. One of the biggest problems is the lack of teacher and student communication, the difficulty of the teacher in solving individual student problems, and the loss of interest in the classes [48]. To solve these problems, teachers must look for new tools and innovative methodologies to improve the distance learning experience [49]. It is important to emphasize that information technologies are increasingly being used in education, and AR together with mobile devices are two of the technologies that have produced the most innovations in this educational field [20; 30; 50]. In addition, the use of mobile devices has increased considerably; approximately half of the students use them to investigate in greater detail the topics covered in class and to obtain additional information about them [51]. Mobile devices are widely used due to their features and benefits such as having information at the user's fingertips, use of online educational material, high portability, universality, and ubiquity [35; 52]. Today, almost everyone has at least one mobile device, and 74.43% of these have an Android operating system [53]. Because of this, the development of learning applications that seeks to cover the widest possible audience focuses on Android devices. In addition, a study conducted in 2017 [19] indicates that the preferred devices for the use of AR technologies are mobile devices, due to their ease of use, portability, and cost, compared to laptops or desktop computers. However, there are other items such as smart glasses that are also being widely used for AR applications [20]. There are several examples of initiatives using AR and mobile devices in education. One of these is a mobile application that allows learning calculus through spatial visualization of 3D objects [23], as can be seen in Figure 1. This application works through an interactive menu that shows mathematical functions, a video of extra information, and the 3D graph of the function. There are also mobile applications using AR in the field of anatomy, which are capable of recognizing bones and muscles to provide the user with interactivity and better learning [54]. On the other hand, a technique currently used with mobile AR applications is interactive books, which are based on the presentation of 3D objects with AR technology when viewing the pages of the book [55]. Cisco's networking academy program has integrated a blended learning model (AR and VR) effectively to prepare its learners for network security positions using online learning courses and e-learning platforms [56]. [PERSON], technology presenter at Cisco and author of \"Virtual and Augmented Reality in Education\" [17], mentions that, being immersed in a highly visual society, the more you can engage learners with visual stimuli, the more likely they are to consume and retain that information. For this reason, it is stated that an AR tool will help both teachers and students to have a much friendlier and more didactic study environment. It is also important to identify the effects of technology integration in educational environments and how they can maximize and enhance learning [50]. The use of AR techniques allows the learner to experience sensations and explore learning experiences that, in some cases, may exceed those offered by traditional lectures [5]. AR uses mobile devices to provide real-world abstraction and contextual visualization; therefore, the use  
Figure 1: AR app interface and its elements (reproduced with permission from ref [23], 2015 Elsevier). of AR in conjunction with smart devices encourages interest and increases motivation for learning [51]. Within education, there have been research studies that evaluate how student motivation can be improved with the use of AR.