An Overview of Mobile Learning for Refugee Students: Juxtaposing Refugee Needs with Mobile Applications’ Characteristics

: The mass inﬂux of refugees into Europe since 2013 and their educational challenges have increased the need for high-quality refugee education. One proposal for addressing these challenges was to leverage mobile devices for educational purposes (mobile learning). Although signiﬁcant research has been done in this ﬁeld, mobile learning’s e ﬀ ectiveness on di ﬀ erent social groups has yet to be explored. The present review paper aims to outline: (a) the factors that challenge refugee education, (b) the use of smart mobile devices by the refugee population, (c) the conﬂicting views about the e ﬀ ect of mobile learning in refugee education, and (d) the proposed characteristics for mobile refugee applications as found in the literature. A juxtaposition of refugee needs with the characteristics of mobile learning apps is attempted. By surveying the literature, the present paper concludes that mobile learning seems beneﬁcial for refugees in two ways: providing refugees access to education and improving the quality of the provided refugee education. However, it is not a one-solution-ﬁts-all regarding their education. At the end, future research proposals are included.


Introduction
In recent years, the mass influx of refugees has exceeded the number of refugees from the Second World War [1]. In 2019, it was estimated that worldwide, a person had to flee his or her country roughly every two seconds [2]. Over sixty million forcibly displaced people, notably from Syria, Iraq, Afghanistan, Asia, and Eastern Africa, crossed the borders that year to seek shelter in Northern Europe and other countries worldwide [2]. In 2015 in Europe, 1.3 million asylum applications were received, far exceeding the number of applications in previous years [3]. The unprecedented number of refugees (over 100 million people) during the second decade of the 21st century (2010-2019) made many researchers talk about a "global refugee crisis" [4][5][6].
Children and teenage refugees have constituted a significant portion of the refugee population. In 2018, the United Nations High Commissioner for Refugees (UNHCR) reported that approximately half of the 25.4 million refugees were under the age of 18 [2], while in 2019, the number of refugee children reached 30 to 34 million [6]. Refugee education has emerged as a priority throughout Europe due to the large number of refugee children, their resulting impact on the composition of schools' student population, and the need to integrate refugees into their host countries. The crucial role of refugee education has been recognized by governments and organizations worldwide [7,8]. The United Nations Educational, Scientific and Cultural Organization (UNESCO) outlined the role of education as an essential tool to "ensure peaceful societies" and prevent intolerance and discrimination [9] (p. 7). Refugees must build their capacity by gaining relevant knowledge, skills, and competencies [10]. However, 13 million youths have been reported as being behind in school [5]. On average, each refugee has spent approximately 17-20 years in exile [11,12]. With that in mind, United Nations Children's Fund (UNICEF) has warned that the risk of a "lost generation" of refugee children will be increased if educational opportunities are not provided rapidly [5,[13][14][15]. Many countries have adopted an educational plan for refugees within their integration policy. However, education remains a challenging task for refugees for several reasons/factors-even with such policies being implemented.
According to the UNHCR, in 2019, only 63% of refugee children worldwide had access to primary education, 24% to secondary education, and only 3% succeeded in obtaining a higher education degree [16]. In 2016, the European Commission proposed the use of technological breakthroughs (e.g., the Internet and smart mobile devices) together with the use of interactive learning through them, as a way of addressing the requirements for education and the faster integration of refugees [17,18]. Although many NGOs, European and UN agencies have invested in mobile devices to provide access and enhance refugees' education, there is limited research on the effect of mobile learning on refugees [14,19,20].
This article aims to outline the field of mobile learning for refugees. The main identified issues include the various challenges of refugee education, how they use smart mobile devices, and the effect (advantages and disadvantages) of mobile learning on students in general and refugee students in particular. Afterward, research findings combine mobile learning apps' proposed literature characteristics with refugees' educational needs. In the end, conclusions and proposals for future research are included.

Methodology
A rapid literature review was conducted to understand the current knowledge in mobile learning for refugees. Based on this aim, a review protocol was developed. The corpus of research was selected based on criteria relevant to the topics mentioned above of the most cited published articles in the English language within the last ten years (2010-2020). Selected literature was retrieved from known databases such as ERIC (Education Resources Information Center), BASE (Bielefeld Academic Search Engine) and Google Scholar by entering the following keywords and Boolean Operators (*, AND): "mobile AND refugee *", "mobile learning AND refugee education", "refugee * AND smartphone *", and "refugee * AND app *." The primary literature search was conducted in June 2020, and an additional search was carried out in September 2020. Available sources of grey literature and the websites of key organizations in the field (e.g., UNHCR, UNESCO, and UNICEF) were included. In some cases, the "snowballing" technique was followed (i.e., citation-based search). Among the 19,700-plus extracted publications, only 29 were found eligible after duplicate removal and abstract screening. After the second literature search, five more articles were added. A total of 34 records were used in this review, in addition to other general citations {i.e., literature regarding refugee education (11 sources), mobile learning (26 sources) or other (21 sources)}.

Challenges in Refugee Education
A significant heterogeneity has characterized the groups of refugee students in terms of origin, language acquisition, socio-cultural and educational background, life experiences, place of residence, living conditions, health, and legal status [21][22][23]. Such heterogeneity adds to the complexity of refugee education and needs to be taken into account. Several researchers have introduced various factors that challenge refugee education [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. In this article, a selected number of factors, including a prior model (see Figure 1) associated with refugee learning, were reviewed and summarized in Table 1. All the gathered factors were classified into five key categories (a. living conditions, b. learning needs, c. emotional needs, d. socio-cultural differences, and e. educational system of the refugee host country), all of which will be analyzed below (see Table 1).  [22,25] Lack of language literacy in their native language [26] Mental health issues and psychological situation [22,24] Cultural background [22,32,33] Absence of a coherent curriculum and non-qualified teachers [26] Health issues [23] Lack of acquisition of the host-country language-Language barrier [21,22,24] Dealing with traumatic experiences [30,31] Issue of lost documents and difficulty in recognizing prior educational award papers [21] Low levels of acquisition of English language [22] Lack of family and social network support [24] Family's educational and socio-cultural background [34] High academic requirements of school subjects-Inappropriate educational material and texts for students with low levels of literacy [35] Lack of digital literacy skills [27][28][29] High socio-cultural requirements of school subjects [30,35] 3.1.

Living Conditions
Refugees spend a critical amount of time moving from place to place, either across countries to reach their desired host country or being transferred from, or between, temporary refugee camps to urban areas [25]. The residence (e.g., living in refugee camps or urban areas) seems to play an essential role in their living conditions and, therefore, their educational performance [14]. Refugees living in refugee camps often experience more impoverished living conditions than refugees living in urban areas, e.g., lack of electricity, internet connectivity, or access to educational institutions [36]. Research has shown that poor living conditions in camps, continual changes in places of residence or

E. Host Country's Educational System
Place of residence [22,25] Lack of language literacy in their native language [26] Mental health issues and psychological situation [22,24] Cultural background [22,32,33] Absence of a coherent curriculum and non-qualified teachers [26] Health issues [23] Lack of acquisition of the host-country language-Language barrier [21,22,24] Dealing with traumatic experiences [30,31] Issue of lost documents and difficulty in recognizing prior educational award papers [21] Low levels of acquisition of English language [22] Lack of family and social network support [24] Family's educational and socio-cultural background [34] High academic requirements of school subjects-Inappropriate educational material and texts for students with low levels of literacy [35] Lack of digital literacy skills [27][28][29] High socio-cultural requirements of school subjects [30,35] All the gathered factors were classified into five key categories (a. living conditions, b. learning needs, c. emotional needs, d. socio-cultural differences, and e. educational system of the refugee host country), all of which will be analyzed below (see Table 1).

Living Conditions
Refugees spend a critical amount of time moving from place to place, either across countries to reach their desired host country or being transferred from, or between, temporary refugee camps to urban areas [25]. The residence (e.g., living in refugee camps or urban areas) seems to play an essential role in their living conditions and, therefore, their educational performance [14]. Refugees living in refugee camps often experience more impoverished living conditions than refugees living in urban areas, e.g., lack of electricity, internet connectivity, or access to educational institutions [36]. Research has shown that poor living conditions in camps, continual changes in places of residence or country, and rising health problems increase the risk of refugees dropping out of school or interrupting their learning [22,23].

Learning Needs
Due to war conflicts and the increasingly aggravating situations in their countries, refugee children usually have gaps in their education. Refugee students find it difficult to cover these gaps while learning a new language and adjusting to their host country [10,31]. Issues such as low or zero acquisition of their native language, lack of knowledge of the host country's language and low level of a "universal" language (English) proficiency, in combination with low levels of literacy and skills due to their stay for extended periods in refugee camps, are usually common [19,22,26]. The "language barrier" is particularly challenging for students, who usually are accepted in the host country's formal educational system, but with no or little knowledge of the instruction language in schools, the chances of falling behind are rising [21,24]. Lastly, although digital literacy skills seem to be essential in the 21st century, refugee women and children may lack such proficiency [27][28][29]. Due to socio-cultural and financial reasons, some refugee families may have only one mobile device, which usually belongs to their male heads. Thus, the opportunities for cultivating their digital literacy skills could be minimal.

Emotional Needs
Refugee students usually have to overcome traumatic experiences in pre-and post-migration periods [31]. A study on Syrian refugees noted that 79% of the refugee children had experienced loss due to a family member's death, and about 60% of the children were eyewitnesses of physical violence or shootings [37]. A significant number of refugee children have lost one or both of their parents or siblings. This fact has resulted in the loss or a lack of children's family network support [31]. Many refugee children also have to cope with the loss of the broader social web of interpersonal relationships, e.g., relatives and friends [31]. The lack of interpersonal networking in their social environment comes in opposition to children's need for belonging, bonding with significant others, communication, and connection with their peers and could worsen the refugee children's already aggravated psychological condition [24]. Torture, war experiences, loss of and separation from their loved ones before arriving in the host country, in combination with loneliness, stress-due to the ignorance of the laws, the language, the culture, and the urban lifestyle-and traumatic experiences in dealing with poor living conditions, racism, and discrimination in the new host country's environment are the usual issues which, according to Cerna [24], seemed to affect refugees' well-being in the long term. All the above traumatic experiences could pose challenges and obstacles to refugee students' academic success [30]. Common mental health issues that have arisen are depression, post-traumatic stress disorder (PTSD), alienation, isolation, and social marginalization [22][23][24]31].

Socio-Cultural Needs
One of the school's essential functions is the transmission and reproduction of its dominant social group [30]. Refugee students have to handle their different cultural backgrounds and are unaware, for the most part, of the culture of their host country. According to Hall's iceberg metaphor model of culture (see Figure 2) [38], the most considerable portion of cultural aspects, which include some beliefs, values, and thought patterns of a society, is hidden, and only through active participation in the culture can it be revealed and learned [39]. Therefore, refugees need time to understand and get used to the culture of their new country. Moreover, refugee children have to simultaneously handle their different cultural backgrounds with the new culture they learn to form their identities. In the case in which refugees' cultural background contradicts the features of the host country's culture, defensiveness, anger, judgments, feelings of superiority/inferiority, prejudices, and discriminatory practices were created [32]. In Western civilizations, the features of culture appreciated in schools include cultural priority of education, work ethic philosophies, parental support level with homework, and ways of resolving conflicts [32].
Challenges 2020, 11, x 5 of 14 appreciated in schools include cultural priority of education, work ethic philosophies, parental support level with homework, and ways of resolving conflicts [32]. The family environment of refugee students dramatically impacts their learning [40,41]. Parents' beliefs about education, socioeconomic class, parental education and work, and parental support in their child's learning appear to affect refugee students' learning process [34]. Remarkably, many refugee parents seemed to prioritize their children's education as a way to faster integrate into the local community [34,40]. On the other hand, in some groups of refugees, girls were dropping out or were denied access to education by their families because, in their cultural background, women are perceived to be the home caretakers [33,42]. Similarly, due to socio-financial factors, male students in secondary education dropped out of school to financially support their families [43].

The Educational System of the Host Country
Issues of lost documents and recognizing the refugees' prior learning and academic qualifications (awarded educational titles/degrees from the refugees' country of origin) remain problematic, hindering the refugees' studies' continuum and entry into the labor market [21]. The readiness of such educational systems aligned with the students' needs and characteristics is another significant point. An appropriate educational policy with a coherent educational program and qualified teachers is imperative [26]. High academic knowledge requirements (e.g., knowledge of some content areas and scientific terms) combined with the lack of adaptation of the study guides and the educational material given to refugees could stand as obstacles to their education [35]. The unspoken beliefs and values are considered the classroom's hidden curriculum that sets students up for success [44]. The hidden curriculum's ignorance might lead refugee students to unacceptable behavior and harmful practices giving their teachers and classmates wrong impressions. Examples of the hidden curriculum include punctuality in arriving at school, raising a hand to answer a question, and asking for permission to leave the classroom [30].
To sum up, refugees constitute a vulnerable social group with particular and complex needs. The recording, knowledge, and understanding of those needs are critical for designing and elaborating any refugee education action. The opposite way (i.e., the lack of taking into consideration the heterogeneity and the complex needs of refugees) could lead, according to Halkic and Arnold [21], to the (re)production of social inequalities and educational outcomes of doubtful effectiveness.

Use of Smart Mobile Devices by Refugees
Smart mobile devices differentiate based on their characteristics (connectivity, portability) from other electronic devices (such as computers and laptops) [23]. As a result, Mark and Chew [45] Behavior Beliefs Values and Thought Patterns The family environment of refugee students dramatically impacts their learning [40,41]. Parents' beliefs about education, socioeconomic class, parental education and work, and parental support in their child's learning appear to affect refugee students' learning process [34]. Remarkably, many refugee parents seemed to prioritize their children's education as a way to faster integrate into the local community [34,40]. On the other hand, in some groups of refugees, girls were dropping out or were denied access to education by their families because, in their cultural background, women are perceived to be the home caretakers [33,42]. Similarly, due to socio-financial factors, male students in secondary education dropped out of school to financially support their families [43].

The Educational System of the Host Country
Issues of lost documents and recognizing the refugees' prior learning and academic qualifications (awarded educational titles/degrees from the refugees' country of origin) remain problematic, hindering the refugees' studies' continuum and entry into the labor market [21]. The readiness of such educational systems aligned with the students' needs and characteristics is another significant point. An appropriate educational policy with a coherent educational program and qualified teachers is imperative [26]. High academic knowledge requirements (e.g., knowledge of some content areas and scientific terms) combined with the lack of adaptation of the study guides and the educational material given to refugees could stand as obstacles to their education [35]. The unspoken beliefs and values are considered the classroom's hidden curriculum that sets students up for success [44]. The hidden curriculum's ignorance might lead refugee students to unacceptable behavior and harmful practices giving their teachers and classmates wrong impressions. Examples of the hidden curriculum include punctuality in arriving at school, raising a hand to answer a question, and asking for permission to leave the classroom [30].
To sum up, refugees constitute a vulnerable social group with particular and complex needs. The recording, knowledge, and understanding of those needs are critical for designing and elaborating any refugee education action. The opposite way (i.e., the lack of taking into consideration the heterogeneity and the complex needs of refugees) could lead, according to Halkic and Arnold [21], to the (re)production of social inequalities and educational outcomes of doubtful effectiveness.

Use of Smart Mobile Devices by Refugees
Smart mobile devices differentiate based on their characteristics (connectivity, portability) from other electronic devices (such as computers and laptops) [23]. As a result, Mark and Chew [45] considered them the most widespread kind of electronic device in history, and their use seems to have an unprecedented role in people's daily lives [5,19,46,47]. According to United Nations Educational, Scientific and Cultural Organization (UNESCO) research, in 2017, 3.6 billion people worldwide used the Internet, which was thought to reach 4.7 billion users in 2020 [17]. A significant portion of these numbers was considered digital literate youths worldwide [48]. As far as refugee populations are concerned, they seem to use mobile devices daily to face everyday difficulties [4,5,49,50]. The research revealed that most refugees own a mobile device, and more than 50% of young refugees use the Internet daily [19,50]. Refugees seem to relate their mobile devices and Internet connectivity to the basic needs for their survival [51,52]. According to the UNHCR, mobile devices are used during the refugee journey and in host countries [51]. During the refugees' trip, mobile devices are used as orientation and service finding tools and protection tools to inform each other of dangers or call a person of trust if they are arrested [51]. Upon the refugees' arrival in a host country, mobile devices constitute essential means for various uses. The ways refugees use mobile devices can be categorized into 12 categories based on the reviewed literature: (1) orientation, (2) accessibility to information, (3) availability of aid services for refugees, (4) availability of education and linguistic resources, (5) word/phrase translation in their native language, (6) admissibility to labor markets and entrepreneurship opportunities, (7) communication with loved ones in the home country, (8) socializing with the local population and other refugees in their host country, (9) money transfer, (10) interactivity with the host government, (11) volunteer coordination, and (12) self-help aid services [4,51,52].

Mobile Learning
Due to the widespread use of mobile devices in everyday life and the benefits they offer, many researchers have begun to explore how to use them in other areas, such as the education sector [53][54][55]. Mobile learning, a new research field in education [56][57][58], began developing gradually in the late 20th century [59], although a significant increase in the use of mobile devices for educational purposes has been observed since 2008 [60] following the release of the first generation iPhone the same year [55].

Advantages of Mobile Learning
The effectiveness of mobile learning in the educational process has been examined thoroughly, presenting mostly positive results [61][62][63][64][65]. In particular, mobile learning positively affects students' performance, increasing their motivation and engagement with the subject matter [66]. A comparative literature survey showed that mobile devices have a more significant positive effect on the learning process than computers [59].
The advantages of mobile learning can be categorized into two groups: functional and learning. The functional advantages, which are based on the characteristics of mobile devices, include (1) the availability of mobile devices, (2) the ease of use due to their portability, (3) the Internet connectivity, (4) the ability to use multimedia, (5) the interaction with the learning material without place or time restrictions and (6) the ability of students to communicate with their teachers and classmates [23,62]. The above functional features of mobile learning formulate the learning advantages, which include: (1) the asynchronous nature of learning, (2) the spontaneity and the active involvement in learning, (3) the rise of students' autonomy, (4) the increase in students' engagement time and motivation for learning, (5) the instant feedback and progress indications, and (6) the flexible roles of students and instructors [23,47,[66][67][68][69][70][71][72].

Disadvantages of Mobile Learning
Although most research papers conclude in favor of mobile learning, mobile learning's disadvantages need to be considered. A comparative literature review from 2007-2014 indicated students' cognitive overload as one of the main disadvantages of mobile learning [73]. Students often feel "lost" or "overwhelmed" by the abundance of information when they are not provided with some support [74,75].
A significant number of research over the past decade showed no difference between mobile devices and traditional teaching methods. A systematic research study from 2000-2008 showed no difference in the assessment test results of students who used mobile devices and those taught by the traditional method (paper and pencil) [76]. Another literature review study from 2001-2011 on educational games' cognitive impact concluded that there was insufficient data on whether educational games on mobile devices improve learning outcomes [77]. However, we must keep in mind that modern mobile devices now have more capabilities than those of the previous decade. In recent years, the following cases of adverse effects of mobile learning have been recorded: students found it challenging to use the proposed applications [78], were not able to perform multiple tasks simultaneously (multitasking), and were detached from their classmates since they used the mobile devices individually [63].
In conclusion, the use of mobile devices in education has been found to have both positive and negative effects on the learning process, as presented above. According to research studies [79,80], mobile devices in education should act as a tool to assist or enhance learning and not replace other teaching methods. Jeng et al. [79] state that the purpose of using mobile devices is not to complicate but to contribute to the learning process. After all, as Cheng, Yang, Chang, and Kuo [80] mention, mobile devices can bring positive learning outcomes only when teaching is designed to incorporate technology properly.

Mobile Learning for Refugees
Mobile learning could be used as leverage for educational purposes in periods of crisis and emergencies. Given the high rates of mobile devices' availability among refugees and the advantages of mobile learning, research seems to support the use of mobile learning in order to enable and enhance education for refugee populations [11,51,81]. According to Lamrani and Abdelwahed [61], mobile learning could contribute to refugee education in expanding refugee access to formal and informal education and improving the quality of the education they receive. According to UNESCO [15], mobile learning could act as a way of averting the rise of a lost generation [5,14,15].
Regarding access to education, it is easily understood that refugees on the move may not carry books or pencils, but it is possible to carry a mobile phone. Many authors agree that mobile learning could contribute to overcoming difficulties regarding access to education for refugees/asylum seekers who do not have the required documents, for refugees who were temporarily living in settlement camps waiting to be transferred, and for those who have settled a long distance away from educational institutions [9,21]. Refugees usually face electrical blackouts and unreliable or limited Internet connectivity [82]. These problems could be solved by accessing offline materials [50,83]. In addition to access to education, mobile learning can also improve the quality of education that refugee students receive [84]. According to a study about refugee students' learning performance at early school age in Tanzania, "access to educational opportunities means nothing if pupils are not learning" [34] (p.9). One of the assets of mobile learning is the provision of personalized learning. Learning based on students' needs and interests can be cultivated, since students' levels can be detected through mobile learning applications, and students can make progress at their own pace [20,85]. In refugee students, understanding their lack of specific skills and knowledge and providing help in scaffolding during their effort seems to have beneficial outcomes [29].
On the other hand, Weibert et al. [20] reported that mobile learning services have not often reached those intended. Navigating through mobile apps can be difficult for refugees [84]. Extended observations of three-year-long fieldwork with refugees in Canada revealed that refugees were often challenged in using Information and Communication Technologies (ICT) since some lacked the required ICT literacy skills and struggled to maintain their security through their digital activities [86]. Mobile apps are not panaceas for refugees. The benefits of mobile learning could not have any influence if the applications' design "lacks coordination, is driven by profit and is decontextualized from the learning context" [87] (p.1). Issues that usually arise after creating mobile learning apps for refugees are the language barrier, the lack of relevance of the content to their everyday lives, and the lack of support. According to UNESCO [47], "the right content may exist; however, it might lack relevance to students" (p. 33).

Discussion: Juxtaposing Mobile Learning Applications Characteristics with Refugee Needs
Drawing on the factors presented in the previous sections that influence refugees' learning, there is a need for these factors to act to determine educational applications' characteristics for refugee students. Thus, it becomes crucial for mobile learning apps' characteristics to match complex refugee needs, towards a better educational experience. Various characteristics were proposed or applied in the reviewed literature about mobile learning applications for refugee students. For this study's purposes, we collected and attempted to juxtapose some mobile app characteristics with the four (out of five) groups of challenging factors to refugee education: the living conditions and the learning, emotional and socio-cultural needs ( Table 2). The fifth group, i.e., the host country's educational system, is omitted because the creation of educational applications for mobile learning aims to provide solutions to the deficiencies of the existing educational system. Table 2. Characteristics of mobile learning applications proposed in the literature.

B. Learning needs
Scaffolding in the use of the application [3,90]. Scaffolding in the approach of new educational content (step by step) [3]. Explanation of the meaning of scientific terms [35]. Ability to develop metacognitive skills (e.g., auto-correction, self-evaluation of progress) [90].

Living Conditions of Refugee Students
Access by refugee students to a fixed Internet network and paid applications, courses, or materials was considered difficult to achieve depending on their place of residence and their family's financial situation. That is why the creation of free applications [14,36,88] not subjected to Internet connection was recommended [50,83,89].

Learning the Needs of Refugee Students
Due to the challenges which refugees face in their education (see Section 2), more support (e.g., scaffolding) is suggested in teaching new learning content [3]. Moreover, refugee students may need more scaffolding to navigate or handle electronic learning resources, since some may lack digital literacy skills. According to Ahad and Benton [92], mobile learning offers tools for creating personalized learning environments with adequate support for refugee students. Scaffolding appears to reduce the risk of cognitive overload and helps to overcome barriers, such as the differences in refugees' socio-cultural backgrounds and the lack of necessary skills and knowledge [3]. This view seems consistent with Demmans Epp's research [90], which highlighted the need to create mobile learning applications that guide refugee or immigrant students to a cognitive and metacognitive level.

Emotional and Socio-Cultural Needs of Refugee Students
One of the solutions proposed for refugee students, in order for their education's cognitive outcomes to be raised, was the creation of multilingual applications in their native language [34]. Furthermore, research conducted on mobile-learning disadvantages showed adverse effects of mobile learning when one-on-one teaching methods (i.e., one student per mobile device) were applied, such as loneliness and marginalization [63]. Other research highlighted the importance of the need for socialization among refugee students-even more than among locals-in order to quickly achieve their integration into the new society [9,14,36]. The above mobile learning's disadvantages, combined with the need of refugee students to socialize with the locals, could be overcome by creating mobile learning applications that enhance the interaction between refugee students with their teacher, classmates, or the local population. Although in most mobile learning applications, refugee students were asked to work and acquire new knowledge individually. Two models have been proposed in the reviewed literature to address the growing need of refugee students for socialization in conjunction with mobile devices' extensive use: (i) the "mixed model" or "blended learning" model, in which the use of mobile learning is combined with the traditional form of teaching [3,46,71], and (ii) the collaborative learning model in which users have to collaborate within the app [73].

Limitations of the Review
The current rapid review paper is not a full systematic review of all the evidence since the number of the searched databases is small. Even though our view is that critical aspects of the subject are not omitted, publications that could enhance this review's heuristic value might have been missed.

Conclusions
Nowadays, many refugee children at school-age globally, and the need for quick responses, as far as their education is concerned, make research on refugee education more necessary than ever to improve the quality of provided education. In this review paper, we aimed to outline the field of mobile learning for refugee students. Mobile learning appears to contribute to refugee education in two ways: providing refugees access to education and improving the provided refugee education quality. However, the use of mobile devices in learning is not a panacea. Many researchers emphasized the need to consider learning needs and refugees' preferences when constructing educational applications. Thus, a juxtaposition of refugee needs with the characteristics of mobile learning apps was considered necessary. In this article, insight into the proposed literature characteristics of mobile learning apps was given, and their association with refugees' needs was attempted. In line with the view of Stead [70] and Lifanova et al. [91], the research on the field of mobile learning and refugee education could act as a proposal to upgrade the quality of education not only for other vulnerable social groups, based on their specific characteristics, but also of all students in general. Recently, the rapid shift to online learning due to the spread of the COVID-19 virus in many countries made the need for mobile learning more imminent. Indeed, our view is that the general outline of factors influencing refugee learning and the apps' characteristics can be applicable for distance educational needs in general.
Further research should be done in areas such as the existing mobile apps for refugees and their characteristics and the existing mobile learning apps' effectiveness [92]. Moreover, literature review research with expertise practice is proposed for up-to-date conceptual frameworks regarding refugee education to be constructed [93].
Author Contributions: All co-authors contributed to data collection and/or analysis of project results. All authors have read and agreed to the published version of the manuscript.
Funding: This research received no external funding.

Conflicts of Interest:
The authors declare no conflict of interest.