Teachers’ Perspectives on Students’ Cultural Diversity: A Systematic Literature Review

: Cultural diversity in schools takes on various forms, including social class, ethnicity, religion and nationality, among other factors that constitute students’ identity, influencing their learning. Therefore, one of the biggest challenges that educational systems face internationally is the effective inclusion of all children and young people in schools. For this process to be successful, the roles played by teachers are essential. Thus, our main objective with this systematic literature review is to expand knowledge and awareness of cultural diversity issues to promote the inclusion of learners from primary to secondary education in Europe. To achieve this, we will highlight teachers’ perceptions of students’ cultural diversity and identify a range of strategies and practices that can contribute to the development of their professional learning. The search was conducted in two databases, Scopus and the Web of Science, and focused on articles published between 2010 and 2022. Of the 3976 identified articles, 41 were included in this study. The findings suggest that teachers consider diversity to be a challenge despite the existence of a favorable view toward students’ cultural diversity. A set of solutions is given for the development of inclusion processes.


Introduction
The Organization for Economic Cooperation and Development (OECD) Programme for International Student Assessment (PISA) results have pointed to students' family and socioeconomic background and migrant status, above other factors, as the main predictors of students' performance at school [1][2][3].It is not new that cultural diversity has been increasing all over Europe, driven by the process of non-European immigration, mainly from the 1960s onward [4], and by the increase in social inequalities, exacerbated by the latest economic crises [5].This cultural diversity brings new challenges for both students and teachers, where schools remain contexts of intercultural tension and the academic performance of immigrants and students from disadvantaged backgrounds still lags behind their peers [6].
According to the UNESCO Global Education Monitoring Report, one of the most complicated barriers to inclusion in education is "the lack of belief that it is possible and desirable", and evidence shows that "one in three teachers in 43 upper and upper middle-income countries in 2018 [. ..] have not adjusted their teaching to students' cultural diversity" [7] (p. 1).From here, another issue emerges related to teachers' professional development, awareness and practices on issues of diversity and inclusion [3,[8][9][10][11].On the one hand, Europe is a linguistically diverse and heterogeneous continent where educating an increasingly multicultural and multilingual population [12][13][14] is a challenge; on the other hand, across Europe, teachers seem to face personal and professional dilemmas related to cultural diversity [15][16][17].
Research suggests the existence of a significant relationship between school culture and the ability to develop inclusive strategies [17] because of the combination of three dimensions: (1) initiative and motivation to learn and to develop professionally (culture of change), (2) collaboration with families and other community members (inclusive policies) and (3) teamwork among school professionals (collaborative work).This results in an increased possibility of transforming teaching practices and strategies and increasing resources to meet students' needs [17].In this sense, it is important to reinforce that all three dimensions are necessary for the development of inclusion in school and all of them must be considered in any school change plan [18].
In this paper, we address the theme of diversity focused on the cultural dimension related to nationality, ethnicity, language, religion and social class [19,20] as a determining factor for the constitution of student identity that influences their learning [7,21,22] and contributes to the creation of diverse classrooms [18,23].
Through this research, we intend to expand knowledge and awareness of cultural diversity issues, and to promote the inclusion of all learners, from primary to secondary education, in Europe.To achieve this, we will (1) explain, from the perspective of in-service teachers, their perspectives, expectations and experiences regarding the management of students' cultural diversity and their inclusion in school and (2) identify a range of strategies and practices that can contribute to the development of teachers' professional learning.
Therefore, the research question guiding this systematic review is the following: what are teachers' conceptions of students' cultural diversity, and what inclusive practices do they promote in the school environment?
In addition to answering the research question through the data collected in this systematic review, we discuss the results by relating them to the approaches of Culturally Responsive Teaching and Intercultural Education.
Despite the existence of many studies on the inclusion of students in school, mainly related to special education and the specific dimensions of diversity, few have engaged in broader research including the various aspects of cultural diversity, and no systematic literature review has been found in this context.

Materials and Methods
As endorsed by the Cochrane Collaboration [24], in this systematic review, we intended to perform an exhaustive search of the literature, checklist-driven quality assessment, complex synthesis using textual, numerical, graphical and tabular methods and sophisticated analysis [25].Thus, data synthesis was organized by a mapping strategy [26] and was used to inform the synthesis stage of the review [25].

Developing a Review Protocol
Aligned with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) model [27], we developed a detailed study protocol that was registered with the International Database of Education Systematic Reviews (IDESR000012).

Search Strategy
The review included any quantitative, qualitative or mixed-methods study focusing on cultural diversity and teachers' roles in students' inclusion.Included studies had to be (1) primary research (quantitative, qualitative or mixed-methods) peer-reviewed journal articles; (2) published in the scope of social sciences (education); (3) written in English, Spanish or Portuguese; (4) published in open access journals, in the final publication stage; (5) set on the European continent, to localise and circumscribe the research to a geographical context marked by a considerable increase in migratory movements; (6) published between 2010 and 2022, to portray the last decade of research in this field; (7) involve, as participants, in-service teachers working in primary and secondary education (ages 6-18) in mainstream schools; (8) focused on cultural diversity, including race, class, ethnicity, religion, nationality, and language, and on the teachers' perceptions and practices related to students' inclusion.The search terms are presented in Table 1.First, the team conducted a search using the terms "systematic review" AND "inclusion" OR "diversity" in the same databases (Scopus and the Web of Science) to map research already done on this topic.It was concluded that the work carried out in this field on school-age students was related to students with special education needs.Thus, studies focused on other dimensions of diversity, such as disabilities, special educational needs (SEN), mental impairments, intellectual impairments, physical impairments, emotional disorders, behavioral disorders (EBD) or psychiatric problems, were excluded, as well as studies conducted in settings beyond Europe, involving preservice teachers or student teachers and students from other educational levels and/or from specific areas (e.g., engineering, medicine).Studies that were not explicitly related to teachers' views (perceptions, attitudes and beliefs) and practices concerning students' cultural diversity and/or their inclusion in classrooms were also excluded.
Second, we conducted indiscriminate readings of the existing research (UNESCO reports, journal articles, books and gray literature) on the topic of students' cultural diversity and how teachers perceive and deal with it in mainstream schools.The PICOS model was used to build a review question that was, on the one hand, understudied in the research field and, on the other hand, restricted to avoid bias [25].Then, the conceptual framework was defined.After initial piloting, the selected search terms, with the additional Boolean search operator combinations, were identified to search databases for records on the 16th of March 2021.In February 2023, we conducted an update as our initial search was more than six months ago; we entered the same keywords into Scopus and the Web of Science.
All searches were conducted to cover full text and abstracts rather than abstracts only.An exhaustive search was carried out over several days, and the last search was recorded in the respective databases for later consultation and confirmation.

Data Management
Metadata corresponding to the definitive search were directly imported from the databases into the EndNote software, and the following PRISMA statement [27] procedures were carried out: (1) identifying records through database searching and identifying duplicated records and (2) screening the records according to inclusion criteria in the first step, whereby titles and abstracts were checked first.
The process for selecting the eligible studies followed a two-stage approach.First, the returned search results were uploaded to EndNote, then into Mendeley, for a second round of deduplication [28].
The first phase of the selection process was managed by a dual-reviewer blind screening approach, where two of the authors independently screened the search results at both the title and abstract screening stage.The two authors then met to review all discrepancies that occurred during individual screening and agreed to resolve them by consensus.
Following this step, a full copy of each paper was acquired to complete the screening exercise through Mendeley software to screen record quality using a framework analysis [29] methodology based on the topic guides being used to gather data.
The full text screening phase was carried out by the whole team.The records selected in the first phase of screening were randomly distributed to each team member.Each reviewer independently read the full study, applied the study quality criteria, and recommended whether the study should be included in the final review [30].The following variables were considered: (1) relevance and validity of the results, (2) applicability of the results and (3) relevance of the results.
There was a second reviewer accompanying this process, and all reviewers met frequently to discuss questions and reach consensus.Excel software was used in this phase to register the decisions on whether to include or exclude screened records.These data management conditions ensured research transparency, validity and reliability.

Data Collection Process
The data collection process validity was carried out considering the intercoder reliability, where multiple authors independently coded the eligible studies using the same coding scheme, guided by a reading sheet based on an evidence-based checklist [27], which included the sections/items presented in Table 2.
For all studies, descriptive data were extracted (Table S1.Evidence table) regarding topic focus, conceptual approach, method, aims, participants, sample size, location, context, study methodology, types of factors investigated and types of outcomes investigated, according to the reading sheet presented above.

Risk of Bias
All studies eligible for inclusion were critically appraised for risk of bias, trustworthiness and methodological quality using an adapted form from the Critical Appraisal Skills Programme checklist [31], where each study was assessed by the appropriate checklist based on its methodological characteristics.To ensure the reliability of the review, multiple authors independently appraised each study using the appropriate checklist (Table 3).As mentioned above, for the synthesis of data from the selected articles, a codification protocol was created that specified all the information to be extracted from the articles.(if yes in 2.) Are the objectives explicit?
3. Is the empirical context clearly described?
4. Did the chosen methodology enable the objectives to be achieved?
5. Are the results consistent with the objectives and the question/s?Applicability of results 6. Do the results apply to the focus of our research?Legend: Y-Yes; ?-Raises doubts; N-No; NA-Not applicable.Include-if relevant to our study (starting point: answer yes to questions 1., 2. and 6.).Do not include-not very or not relevant at all to our study.

Articles Identified and Selected
The search strategy yielded 3976 studies for possible inclusion.After removing duplicates (n = 322), 3674 records were screened at the title and abstract level.At this level, 3086 articles were excluded due to exclusion criteria.In phase two of the screening process, 568 abstracts were analyzed, and 373 records were not retrieved.Full-text assessments of the remaining 195 articles were independently conducted, and 154 were excluded because they did not meet the inclusion criteria.A total of 41 articles met the inclusion criteria and were deemed eligible for the systematic review.Figure 1 provides a flow diagram of the study selection process, which was adapted from PRISMA [27].

Results
The analysed studies address our research question, providing insights into teachers' perceptions about cultural diversity and inclusion and a wide range of inclusive strategies and practices developed by teachers.
These results should be seen as cautious recommendations for further investigation in relation to students considered culturally diverse.

Results
The analysed studies address our research question, providing insights into teachers' perceptions about cultural diversity and inclusion and a wide range of inclusive strategies and practices developed by teachers.
These results should be seen as cautious recommendations for further investigation in relation to students considered culturally diverse.

Study Characteristics: Settings, Sample, Dimensions of Cultural Diversity
The European countries where the studies were developed are distributed as follows: Austria (n = 2), Czech Republic (n = 1), England (n = 3), Finland (n = 3), Germany (n = 2), Ireland (n = 2), Italy (n = 2), Netherlands (n = 3), Norway (n = 2), Portugal (n = 2), Romania (n = 1), Spain (n = 16), Switzerland (n = 2) and Turkey (n = 3), with one article reporting studies developed in multiple countries.Considering the specificities of the educational system in each country, and regarding the relationship established between the students' age and the year of schooling they attend, we verified that the studies were focused on working with children and young people between the ages of 6 and 18 years old, without a significant difference regarding this variable.
Participants were essentially teachers since they are the privileged source of information for our work.Although several studies have been found in which other agents participate (head teachers, social workers, families, coordinators, psychologists, students, intercultural mediators and other technicians), the data we have analyzed correspond exclusively to the perceptions of the teachers themselves.
The dimension of cultural diversity that appears most frequently is linguistic diversity (n = 25), which is associated with teaching migrant, immigrant, refugee or bilingual students.This is followed by diversity related to nationality (n = 18), which always appears associated with research related to linguistic diversity, followed by ethnicity (n = 9), with the teaching of Roma students being the one that stands out (n = 5).Socioeconomic background is the third dimension with the greatest impact (n = 11), and religion is the dimension of cultural diversity that appears least frequently (n = 3).Table S2 provides a synthesis of the characteristics of included studies.

Teachers' Perspectives on Students' Diversity and Inclusion
At the level of teachers' professional development, the challenges are associated with the feeling of an inability to support all students and the negative interference that parents can have in the teaching-learning process [17,[32][33][34][35][36][37][38][39] and in the school culture [40][41][42][43][44][45][46][47][48][49][50].It is evident that there is a view of diversity as a challenge, and it arises that teachers do not feel prepared to fulfil students' diverse needs, especially those related to linguistic diversity.Teachers report, in this regard, the difficulties associated with the language barrier (mother tongue versus language of schooling), the prevalence of inappropriate student behavior associated with what they refer to as a 'culture of marginalization' and the learning gaps and difficulties reported by students [17,33,[35][36][37][38]40,42,[45][46][47]49,50].
On the other hand, and without significant differences in frequency, we found evidence on the existence of a favorable view of teachers toward students' cultural diversity, especially at the discourse level.These studies highlight the perspective of diversity as an added value, as a reality that enriches learning and coexistence among all, moving away from the idea that students should be grouped according to their origin, culture, or mother tongue [16,42,43,48,[51][52][53][54][55][56][57].The data indicate that teachers are motivated to work with all students, that they recognize the importance of diversity for their own learning and for their personal and professional development and, in the case of students who learn English as an additional language (EAL), highlight their ease of learning [5,36,41,[58][59][60][61][62].
The results of the studies included in this systematic review suggest the existence of different levels of awareness about diversity among teachers, justified by the teachers' levels of knowledge, which range from those who have more knowledge, experience and sensitivity to deal with diversity specificities [5,8,16,53,[59][60][61] to those who are at lower levels regarding these dimensions [8,32,40,50,63].Thus, teachers who show the highest levels of awareness of diversity are those who (i) believe that multilingualism and student participation are opportunities for their own learning [16,53,59]; (ii) consider that each student should be seen as a unique individual, with their own characteristics and needs [60,61]; (iii) are opposed to grouping students according to their culture [5,48]; and (iv) are able to modify classroom instructions and strategies [8].On the other hand, it remains a common view that the presence of refugees or linguistically diverse learners slows down the teaching process, which is why these students should be taught in separate classrooms from their peers [32,50].
In certain settings (n = 8), immigrant, Muslim and Roma students are seen as problematic and/or less able when compared to others [17,32,39,[44][45][46][47]64].Some of these studies share the view of inclusion as compensation for students' difficulties, implying poor student participation, and teachers seem to be unfamiliar with the term "inclusion" [17,40,47,65].In these cases, there are teachers who consider that inclusion corresponds to an overload of teaching work that is not part of their competencies [33,40] and teachers who consider xenophobic and discriminatory attitudes among adolescents normal, so they do not apply measures to correct them [66].
Some studies (n = 5) highlight the gaps regarding teachers' knowledge and experiences in managing diversity in the classroom [8,16,40,41,63].Only two articles mention that teachers have knowledge about the diversity of students [54,56], and there are few articles (n = 2) that explicitly express the motivation of teachers to support inclusion processes in school.Although this is not the perspective of most cases, it is a relevant notion that emerges from the data analyzed and it is important to bring it into the discussion, as it justifies the relevance of the proposals for professional development strategies that are developed in the following point.
Another interesting finding that becomes explicit in one of the studies relates to the fact that there is a certain dissonance between what teachers believe and what they practice, since they reveal themselves to be sensitive to diversity issues, on the one hand, but do not assume (or do not feel empowered) to act differently to meet the needs and characteristics of the students [66].On the one hand, the opinion of families is valued and encouraged, and they are motivated to support the good performance of students [36,43], on the other hand, teachers recognize that the lack of means available to students impacts their performance [36,57].Although these data cannot be generalized to the studies analyzed, they permeate some school cultures in a strong way.
Summarizing, teachers, in general, have positive perspectives regarding the diversity of students and, simultaneously, the vast majority point out challenges to the management of diversity in the classroom, which are considered constraints to the development of inclusive education, such as language barriers (mother tongue versus language of schooling), inappropriate student behavior, learning gaps and difficulties, or the negative interference of parents.

Strategies and Practices Developed by Teachers
Regarding strategies and practices used by teachers, we found, with greater frequency, the development of practices that allow the sharing of customs, cultures and traditions specific to the students' country or ethnicity, through stories, vocabulary, books, gifts, photographs, games or gastronomic recipes, during lessons or in moments created for this purpose [16,17,41,44,49,52,57,58,65].At the school level, multicultural breakfasts and celebrations of religious events are promoted.Although most teachers consider these practices to be enriching and valuable for the development of students' inclusion, in two of the texts analyzed, these activities are carried out as extracurricular events or as project work and are seen by some teachers as having little impact on students' lives because they do not bring about effective change [57] or because teachers consider that diversity issues should not be managed in the classroom [40] but by other professionals, such as psychologists or cultural mediators.
Still within the scope of strategies and practices developed in the classroom, a revealing aspect of teachers' knowledge about the principles of inclusion stands out: the creation of learning environments where students feel safe, in this case, to make use of both their mother tongue and English [49,52,54,55,59,64].Mostly concerning linguistic diversity, teachers highlight the importance of individualized support (e.g., providing extralinguistic support materials) and the feedback given to students [39,44,48,64].Some studies (n = 3) explicitly point to the need to break with traditional models of knowledge transmission [34,42,49] in favor of more participatory approaches linked to constructivism and enactivism [42,49,61] or highlighting the advantages of developing communities within schools, involving teachers, students, parents, school staff and members of the community [34].
Evidence suggests that teachers draw on methods and strategies specific to their discipline or their own professional culture to address diversity and promote inclusion of all learners [53,60,61,63]: (1) the methods "Kind op maandag" [Child on Monday] and "Startpunt" [Starting Point], in religious education classes are mentioned [53]; (2) the use of "service-learning", relaxation activities, cooperative learning, gamification, interactive groups or activities promoting emotional intelligence [61]; (3) music education practices in which all students participate, are challenged and exposed to new stimuli [60]; (4) the use of digital tools to communicate and to support mixed-ability students [48,63,64]; (5) the "use of mediation tasks to develop bilingual discourse competence as part of subject-specific literacy" [64] (p.8); and (6) the use of specific approaches to teach languages such as CLIL (Content and Language Integrated Learning) [44,64].
It is important to highlight the existence of practices that attach significant importance to students' voices [16,41,61,68], mirrored in activities such as joint decision-making on rules, cooperative learning tasks, quasiaction research with students and teacher collaboration in pairs, or through stimulating students' argumentation, starting from their own experiences.Family participation emerges as a relevant strategy, although in many cases, it does not occur with the desired frequency [35,36,43,62,65].Measures that involve families include their participation in school assemblies, in the classes themselves, as volunteers [35], the development of practical, day-to-day parental support practices linked to food care, schedules and healthy living habits and other areas in which families show weaknesses, such as the language of the country they are in or digital literacy [43].Parents are also involved in the teaching-learning process through 'learning development dialogs', a practice developed in Austria where parents, students and teachers discuss student performance and progress and potential improvement actions [36].

Teachers' Professional Development Related to Students' Diversity and Inclusion
Regarding professional collaboration, although there are some references to the existence of interprofessional collaborative practices, such as coteaching or joint planning [16,33,54], research suggests that collaborative practices are insufficient to overcome the constraints that the inclusion process may entail [16].Other strategies that emerge in the studies reviewed are the following: (1) the habit of sharing pupils' difficulties among teachers [59][60][61]; (2) the development of assessment practices based on formative evaluation and on students' participation during the lessons [44,64]; (3) the use of evidence to inform teachers' practices [54]; (4) collaborative work between teachers through collaborative supervision-intervision practices [16]; (5) the use of materials shared by specialist teachers, in this case, the language teachers [48]; (6) forming mixed-ability groups as a way to foster opportunities for learners' support; and (7) the concern with the type and the amount of homework provided [44].
The results of the studies included in this systematic review clearly point to the lack of training and experience that teachers feel makes it impossible or difficult for them to work with and support all students [8,16,36,37,40,52,59,62,66,67].The lack of training is mentioned by teachers, both at the level of their initial training and continuing training, along with the instability of educational policies and support from which teachers and schools benefit [34,36].For instance, teachers reveal that not having sufficient knowledge of other languages makes them feel insecure and lack confidence [52], which can exacerbate difficulties in including students and managing the linguistic diversity that exists in classrooms.
On the other hand, we found contexts in which teachers consider themselves to have sufficient training due to their experience and the result of attending training courses throughout their career [54,62], although this is not the case for most teachers.Teachers report having received specific training to improve students' performance, which they consider to have a positive effect [16,54].
Two interconnected factors that teachers consider relevant in this process are the knowledge of students' experiences and the dynamics of their cultural heritage [50], as well as the learning they do with students and about students [57].In this regard, some of the professional development strategies that emerge in the studies included in this paper are as follows: (a) implementing students' voices as a pedagogical tool to address diversity [57]; (b) promoting cultural immersion programs targeted at teachers [8]; (c) forming a learning community that includes students and families [34,57]; and (d) learning simple vocabulary in the students' languages to better welcome them [37,48].
The data suggest that teachers are isolated, developing their practices individually [16,57].In this sense, one of the solutions suggested involves creating spaces where teachers discuss their teaching in a reflective way and where they are simultaneously challenged [8,57,60].

Discussion
This systematic review aims to answer the following research question: what are teachers' perceptions of students' cultural diversity, and what inclusive practices do they promote in the school environment?To find a set of answers that would rigorously address the identified problem, we built three categories of analysis, presented in the previous sections: (1) teachers' perceptions of diversity and inclusion, (2) strategies and practices developed by teachers and (3) teachers' professional development related to students' diversity and inclusion.
As we stated at the beginning of the article, the three-dimensional proposal for the development of schools, including a culture of change, inclusive policies and collaborative work [17,18], permeated the whole research process, so the look at school culture underlies the categories of analysis of this work.According to Abacioglu et al. [51], strengthening school culture involves transforming the context, policies and cultures to eliminate institutionalized discrimination, allowing all students to experience equality and cultural empowerment.Therefore, in this section, we aim to discuss the results regarding teachers' perspectives on student diversity and inclusive practices and establish connections with Culturally Responsive Teaching (CRT) and Intercultural Education (IE) approaches.

Teachers' Perspectives on Student Diversity and Emerging Inclusive Practices
According to the first category of analysis, the results of this systematic review seem to be aligned with the literature: notwithstanding the positive perceptions and beliefs, in-service teachers tend to see cultural diversity as a challenge [69][70][71].The results of this systematic review point to the relevance of teachers' cultural background and professional experience [16,17,47,54,62,63,67] as factors that facilitate or hinder the development of inclusion, depending on each teacher's professional capital.
Regarding teachers' perspectives on students' cultural diversity, we highlight the view of diversity as an asset and as a potential facilitator of inclusion.Even so, we have reservations about saying that we are dealing with a sample of teachers who fit the profile of "culturally responsive teachers" [72], who have positive beliefs about cultural diversity and act as reflective practitioners [41].Understanding differences is not enough in itself; they must also be valued [50].
The aspects that teachers in the studies included in this systematic review point out as the most common difficulties among students who are considered 'culturally diverse' include gaps in skills, knowledge and language, different moral values and lack of motivation and are very often related to the drawbacks of their family contexts [35,42,[45][46][47]50,62,63,66,68].
Family contexts are a relevant factor in this process, and one to which teachers attribute importance.In some settings, in addition to being valued, families are encouraged to actively participate.Teachers' reports reinforce the relevance of the role that families play, something that is reflected in the literature, since the arrival of students with diverse linguistic and cultural backgrounds, although presenting challenges to conventional school communication systems, should be seen as an opportunity, as it may promote all students' learning for an increasingly global world [63].
To empower teachers with practices and strategies that can be effective in responding to students' diversity [12], we highlight the importance of some professional development strategies that emerged in the studies that make up the corpus of analysis of this systematic review such as differentiated instruction.It "is at the core of inclusive education as it is tailored around the differentiation of approaches to serve various student needs through a blend whole-class, group and individual instruction formats" [3] (p. 285) and can adopt a range of strategies, for example the differentiation of teaching methods and techniques, as well as differentiated activities and small group work [32,44,64].
The use of digital technologies is also seen as another strategy that "can serve as a tool to support teachers in adapting to different learning styles and in meeting students' particular needs" [3] (p. 285).Simultaneously, it can promote students' engagement by providing scope for a range of different learning activities, and it facilitates communication with mixed-ability students [3,48,62,64].
In addition, we underline the importance of the development of projects at a European level that can contribute to the development of synergies and partnerships between different contexts, as well as the development of initiatives and practices that engage the students' families [17,[34][35][36]43,62].

Culturally Responsive Teaching (CRT)
According to research conducted by Soylu et al. [50], in cultural responsiveness, it is more important for teachers to have ideas and use strategies to make those cultures meaningful in the classroom than to ensure that all students achieve the same level of cultural background, and having knowledge about the students who attend their school is the main and most common need of CRT [50,[72][73][74][75][76][77].
Regarding language learning, research has shown that "teachers must understand sociolinguistics, appreciate linguistic diversity, and advocate for multilingual language learners" [76] (p. 2), which is confirmed in this systematic literature review [44,48,58].
Allied to knowledge about students, the fact that teachers promote an environment where students feel safe and valued is fundamental, as it appeals, among other aspects, to motivation [77]; otherwise, students may develop feelings of low self-esteem and alienation toward school [9].In this regard, the literature warns us about the impact that teachers' positive or negative reactions can have on the self-esteem and academic performance of students from different cultural, ethnic and linguistic backgrounds [10,50].
Culturally responsive teaching (CRT) focuses on awareness and appreciation of the social structure to which students belong, the language they use and their cultural identity [77].The data indicate that some of these teachers are prepared to make use of CRT [77], although they do not make it explicit as such.The idea underpinning the model is that culture, social class and language influence students' learning styles, behaviors and thoughts [50]; thus, CRT "uses students' cultural experiences and knowledge; supports students in maintaining their cultural identity, native language and connections to their culture; provides multiple opportunities to demonstrate what students learn; incorporates different perspectives; and empowers student sociopolitical consciousness" [41] (p.342).
For successful CRT, teachers must avoid the trap of a deficit or deprivation perspective and instead recognize the importance of students' cultural and intercultural capital [78].The fact that these teachers maintain high expectations of student performance may be a determining factor for their academic success [38,41,61].Another aspect that should be emphasized is related to the need to support and value the cultures of all groups (e.g., religious, ethnic, racial), challenge prejudices, stereotypes and discrimination and ensure that all students have equitable educational opportunities and access to knowledge regardless of their cultural backgrounds [47,51].
In this systematic literature review, some cases were found in which this concern with interculturality permeates the sphere of action of teachers who, on the one hand, adopt practices to eliminate prejudice [37,51,56] and, on the other hand, design their action plan through education for respect and tolerance [62,67].In contrast, we found a minority of teachers who consider discriminatory attitudes normal among students, so they do not act on this issue in the school context [47,66].

Intercultural Education (IE)
In this reflection, we move a little further toward intercultural education (IE), which goes beyond fostering tolerance but which aims to develop (a) respect through dialog between different cultural groups [79]; (b) the ability to establish relationships between the culture of origin and the foreign one; (c) a cultural sensitivity and ability to use a variety of strategies to establish contact with people from other cultures; (d) the ability to play the role of cultural intermediary between one's own culture and the foreign one and to resolve situations of conflict and cultural misunderstandings; and (e) the ability to overcome stereotypes [56].
According to Bleszynska [80], IE is "an applied social science that engages in exploratoryexplanatory, adaptive and transformational functions for individuals, institutions and social groups" [80] (p.537).This intersection refers us to the need to look at IE and CRT [81] as allies in the process of educational inclusion, not forgetting the challenges that these may entail, such as the lack of theoretical knowledge by teachers, that goes beyond the dominant discourse on cultural differences and the constraints in implementing practical solutions to the dilemmas faced in schools [40,82].The results of the present research suggest that there is still a long way to go toward IE, despite finding teachers with this vision and sensitivity.Given most of the conceptions presented by the participating teachers in the studies that we incorporated in this systematic review, it is confirmed that diversity management involves promoting a school culture where everyone's difference is considered wealth and not poverty, is managed as an opportunity and not a problem, and contributes to personal and collective development [40] (p.77).The same premise is advocated in the IE and CRT principles.
IE constitutes a robust response to the difficulties and dilemmas detected in diversity management, which has already been discussed and/or implemented in some contexts [16,17,37,65,66], although the challenges underpinning its applicability in practice are recognized due to the gaps identified in both teacher training [15] and classroom management literature [11] and the fact that classroom management is often presented as a culturally neutral subject [40].

Conclusions
The included studies show that teachers' sensitivity to students' diversity issues can improve their learning.Some teachers explicitly indicated that inclusive education, in the sense of every student learning together, improves the academic success and social skills of disadvantaged learners [32,34,49].At the same time, we concluded that the majority of teachers see cultural diversity as a challenge that many do not feel prepared to face, although some of them do see diversity as an asset.
According to van Middelkoop et al., teachers who recognize diversity among students are more alert and empowered to use different didactic and pedagogical approaches than teachers who ignore cultural differences [83].The fact that there are teachers who claim not to change their teaching methods [40] reveals the existence of gaps regarding knowledge about CRT.Furthermore, research shows that if teachers do not plan learning activities according to the cultures of their students, this can lead to negative consequences for children, families and the social group to which they belong [84], and worldwide evidence shows that "culturally responsive teaching practices have a positive impact not only on students' learning but also on their engagement and psychological well-being" [3] (p. 285).Thus, teachers and students must also develop strategies to support all students' acceptance and respect for themselves and others [85].
In addition to teachers' sensitivity, their own motivation emerges as a relevant aspect as well as their personal and social development [15], which include the commitment to diversity, both at an individual level (the teacher him-or herself) and at the level of the school as a whole [16,37,61,66].Thus, one of the strategies pointed out involves the development of intercultural projects.Nevertheless, it is necessary to look at this type of initiative with some reservation, as there remains a tendency to define as "intercultural" any initiative related to diversity, often in the form of projects such as those listed, which tend to emphasize stereotypes and to simplify the complex webs of meaning hidden by cultural diversity [80,86,87].
The development of collaborative strategies, such as coaching or classroom observations [16,36,68], emerges as relevant tools in the literature to address classroom challenges and tensions [85,88], and our reflection goes further, underlining the power of professional learning communities where groups of three or four teachers come together to foster collaborative work, intending to share experiences, reflecting on their lessons and trying to develop a culturally responsive lesson [89].
Responding to cultural diversity is a difficult concept and undoubtedly needs further clarification, especially regarding classroom practices [36].In this sense, teacher selfreflection is crucial for creating culturally relevant teaching practices [47,74].Thus, it is important to underline that IE and CRT constitute a possible positive response that can break down the entrenched and isomorphic beliefs and practices about cultural diversity that still exist in schools in Europe and promote both the success of culturally diverse students and the construction of a more caring and fair society.

Implications, Limitations and Future Directions
In this research, we find a set of implications, starting with the expansion of knowledge about a global and emerging reality in today's society and motivated by various social, environmental and economic factors, such as the increase in migration flows, the emergence of new diseases that affect the globe (e.g., COVID-19), the increasing mutation and volatility of skills, interests and needs of students, or the geopolitical conflicts that are affecting the world and Europe, in particular.This work also calls for reflection on policies, cultures and practices adopted by teachers in Europe and aims to convey sensitivity and awareness about teachers' perceptions and practices in relation to the cultural diversity of learners.As possible solutions, the development of IE incorporating the CRT model emerges.
Regarding limitations, we consider the fact that the research was conducted using only two databases and the exclusion of gray literature (doctoral theses, etc.) and other types of publications besides peer reviewed articles as factors that restrict the extrapolation of the conclusions to other contexts, as well as the fact that the research was restricted to European countries, and the chronological cutoff that, for reasons of study feasibility, could not be more comprehensive.
Finally, regarding possible future research, it is considered very relevant to explore other dimensions of student diversity and to focus on in-service teacher training, preferably aligned with CRT and, inevitably, with IE.We have assumed in this study the centrality of teachers and their practices for inclusive education, and this stance brings out the perception that specific studies are still needed on the aspects that limit innovation and creativity on the part of teachers.

3 . 1 . 2 .
Year of publication (d) Context: country, education level, participants, publication type, bibliographic reference 2. Motivations and research questions 3. Objects of analysis 4. Objectives 5. Theoretical/conceptual frameworks: (a) Does it refer to any of our study key concepts?(b) Description: Articulation of the Theoretical Frameworks/Conceptual framework (c) Other interesting theoretical contributions to the topic 6. Methodologies, Procedures and Participants (full description) 7. Main contributions (results of the empirical study): (a) Which dimensions of diversity are addressed (b) Is detailed information provided for each of these dimensions?If no, please indicate which dimensions are covered in the article (c) Are there any data/results on teachers' perceptions of student diversity?If yes, what is the evidence on teachers' perspectives, attitudes and beliefs towards student diversity?(d) Are there any data/results on teachers' perceptions/conceptions of educational inclusion?(e) What are teachers' perceptions of inclusion?(f) What strategies/practices do teachers use to promote inclusion?(g) Is there any evidence of barriers/facilitators to inclusion identified by teachers?(h) What barriers/challenges to inclusion do teachers identify?(i) Is there evidence of a link between aspects of teachers' perceptions/practices of inclusion and students' educational success?(j) What aspects are linked?(k) Is the evidence sufficient for the links to be considered adequately demonstrated?Justify.(l) Is there any evidence of teachers' professional development and in-service training in relation to diversity/inclusion/students' educational success?(m) What teacher strategies/practices can contribute to their professional development?8. Limitations, Implications and Lines of Future Work Table Checklist for the assessment of the quality and the reliability of the studies.Assessment of the Quality and Reliability of the Studies Does the research question/s relate to our question?(if yes in 1.) Is the research question/s clear?Do the objectives relate to the aims of our research?

Figure 1 .
Figure 1.Flow chart of the searching process according to the PRISMA protocol [27].

Figure 1 .
Figure 1.Flow chart of the searching process according to the PRISMA protocol [27].

Table 2 .
Reading sheet items.

of the Quality and Reliability of the Studies 7
. The context of the study is representative of real life (dimension from 1 school?)