One of the main challenges for teachers working in rural schools lies in addressing the inherent heterogeneity in multi-grade classrooms, which encompasses students of different ages and characteristics. This is mainly done through changes in methodologies in teaching and learning processes  to enhance the pedagogical and inclusive value of rural schools. This represents a challenge for teachers to implement active-participative, innovative and globalised strategies of multigrade didactics (Bustos, 2007). Nevertheless, these changes must be accompanied by appropriate and pedagogically significant teaching materials that allow the development of multigrade didactics, adapting the educational response to their class diversity (Boix & Bustos, 2014), avoiding the hegemony of the actions carried out in urban graded classrooms and taking into account the idiosyncrasies and particularities of this kind of school (Abós Olivares et al., 2021; Terigi, 2008). The scarcity of specific didactic resources for multigrade teaching and learning, as well as the lack of knowledge about the nature of these resources and their suitability (Brown, 2010; Msimanga, 2019) is a worldwide identified problem and a recurrent need, according to various scientific publications on rural education internationally (Bagley & Fargas-Malet, 2021; Coladarci, 2007; Carrete-Marín & Domingo-Peñafiel, 2021). The inadequacy of the current existing resources is obvious and their creation and selection proves an extra difficulty for teachers in those environments (Juvane, 2005). 

This paper presents the results of an international research project whose main objective is to respond to this need for identifying and clarifying the state of the art of multigrade teaching resources. Our aim is to analyse the concept of multigrade teaching resources, to provide a clear definition for them and to characterize the types of  resources used by teachers in rural schools. 

A systematic literature review considered all published research articles  related to teaching materials in rural schools in the Web of Science, Scopus and Google Scholar databases in response to a query for the following terms: “rural school, “teaching materials”, multigrade materials” and “rural areas”. The central research question is the following: What are the main findings that could help to determine how multigrade teaching materials are conceptualized; and what is there a golden standard for them? In order to answer this question, the following objectives are set out: (1) To describe and analyse the concept of multigrade teaching resources; (2) to review and analyse the types of didactic materials used by teachers in rural schools reflected in international publications; (3) to identify opportunities and needs regarding didactic materials; (4) to identify the dimensions to create and select multigrade teaching materials to be pedagogically significant. 

From a total of 332 research papers identified in the field of rural multigrade teaching, only 33 papers were selected for further analysis through rigorous selection criteria. Our  preliminary results show the need to create materials that are adapted to the contextual reality of rural schools and involve students actively in the learning process, as well as a   need for platforms to share and disseminate resources among teachers in rural environments internationally in order to improve their training needs, receive support and facilitate knowledge of available resources. Finally, a proposal is put forward to define some criteria to be taken into account in teaching practice in order to aid teachers in the development of these resources. 

A rigorous systematic review is carried out of all scientific publications belonging to the Web of Science and Scopus databases from 1992 to 2020 and between 2010 and 2020 for Google Scholar. The latter was included to broaden the range of publications of a more informative nature. All the databases were reviewed with the same search parameters. A systematic search was carried out combining Boolean indicators with the main concepts that allow us to define and present a link with the object of analysis. A total of 332 papers were identified. For the paper selection process, the phases of the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow chart were followed (Moher et al., 2009). The research procedure was characterised by an initial heuristic phase based on the identification of all publications from the selected databases. In the screening phase, the results were filtered out excluding duplicates. After deleting duplicates, 294 sources remained. Results that did not meet the search objectives were also removed by the authors after reading the title, abstract or keywords. iIn the adaptation phase, the full text of the resulting articles was reviewed based on predetermined selection criteria for their possible relevance. Finally, in the last phase of the process, only the publications to be analysed in the systematic review were included. The resulting articles were recorded in descriptive tables or guides for qualitative synthesis. From here, the information was managed and classified with Mendeley's programming and Excel tables. An initial phase of data reduction was performed with Atlas Ti through a system of codes and categories, performing various descriptive analysis actions (reporting of codes, frequency of events, citations, memos and word clouds) to organise and describe the information obtained. In a second phase, the results were critically interpreted (analysis of code networks, analysis of interpretation of citations or tables of co-occurrences) in order to enable theorisation. Finally, an analysis of 33 publications was carried out.

The revision concludes that there is a lack of a consensual definition of multigrade teaching materials in the context of rural school. This research has made it possible to analyse the concept and situation of multigrade teaching materials, proposing a definition and thus establishing a basis for responding to the difficulties that teachers have in understanding the nature of these resources and being able to create them. The results show that textbooks and digital resources are the most widely used materials. Many publications show that despite teachers' efforts, those resources are not adequate (Boix & Bustos, 2014). There is a lack of suitable materials for multi-grade classrooms. In our work, we present the dimensions that must be considered for their adaptation, taking into account that teaching materials must be deliberative in any case, and that they must be adjusted to each classroom and context by teachers in rural schools, thus ensuring their effectiveness (García-Prieto, 2015). This review also highlights the need for creation of networks among teachers. The results show that improvements in teacher training should be implemented, considering the specific configuration of rural schools, as most of them are self-developed. It is necessary to encourage the creation of specific teaching materials to facilitate multigrade work. Finally, this research establishes some dimensions that should be taken into account in the creation of curricular materials that allow their adaptation to multigrade classrooms, promoting the inclusion of all students, and helping teachers working in those rural settings. Thus, this paper contributes to reflect on the state of the art of rural education teaching resources and to envision possible challenges and solutions to improve their creation, thus facilitating more effective teaching. The scarcity of publications on the subject and the need for it underlines the importance of the results of the present study.

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