## 1 Introduction and Background
Thus, by using these resources students can improve their visuospatial skills, problem solving, organization, reasoning, planning, processing speed, etc., while acquiring knowledge of the subjects [22; 23; 27; 31]. These skills need to be worked in the classroom to achieve competence development, necessary for academic and work life [32]. Similarly, digital materials can help teachers to incorporate active learning in the classroom, provoking interest in their students and motivating them towards a better learning. This type of digital materials would support various teaching methodologies such as Flipped Classroom [33], CLIL (Content and Language Integrated Learning) [34] and project learning [16; 32]. In this last point, they can provide support as complementary material for classroom work or information consultation. Other forms of classroom implementation would come with activities to practice acquired knowledge, reinforcement activities, review or homework and teaching assistance for explanations in the classroom [13; 16]. On another note, the actual use of digital material by teachers mostly depends on their perception of personal comfortability and skillfulness with technology. Other factors include their knowledge about the devices and their different contents, as well as their professional abilities when integrating these into teaching programmes [35]. In addition to training, another factor constraining implementation is the attitude that teachers express towards these materials [2; 35]. Bigger skills in handling them relate to more positive attitudes towards the use of digital material. This conclusion underscores the importance of teacher training in the curricular adaptation of these resources [35; 36]. Teachers also play an essential role in making the usage effective through their commitment to integrate technology into the teaching process [37]. Therefore, the use of digital material increases in teachers that feel motivated to learn about it and use it [29]. Although students are digital natives, it is critical for achieving educational goals that teachers emphasize the point of using such devices is to serve as tools for work, not recreation [30; 38]. In that sense, knowing how to properly use digital resources can lead to support meaningful learning in the classroom [1], not leaving apart the central fact that learning consists of many more variables, such as social interaction and cooperation, needed to be trained along too [4]. Another factor to highlight is the design of the material. A better design, accessible to diversity and consistent, will increase the amount of teachers and students using it [2]. Designing digital educational material is a multidisciplinary field in which pedagogical, computer engineering and psychological profiles get involved with game designers in a common task [10; 36]. Although certain frameworks have been developed, attempting to cover both pedagogical and software bases for the design of digital educational material, there are still discrepancies and variables to incorporate in order to achieve the goals of empowering students' learning and skills development [20; 36; 39]. Pedagogical models or frameworks for content development are diverse. They range from those that seek to relate game mechanics, incorporated in many of these activities, with learning [20; 39]. Others show materials that focus design from pedagogical theories for learning, as the cognitive theory of multimedia learning [40], other cognitive or constructivist theories [27; 36; 39], and models for materials based on multiple intelligences [41; 42]. Interactions made via electronic devices can improve and support better learning, should an effective and consistent design be developed among the various disciplines involved [36]. There is still no guide that defines unitary designs or how to evaluate these materials. This is perhaps due to the diversity of variables involved in these processes: educational areas, age ranges, amount of teachers, types of interaction.