The aim of this study is to reveal the keys with regard to obstacles or barriers and facilitators or levers, that curricula represent on the path to designing an inclusive education system in Spain. Specifically, our research geographical area is Andalusia, which is a region in the south of the country that is characterised by rather depressed socioeconomic circumstances that result in high levels of educational failure and early school dropout.

International bodies have already pointed out that "the curriculum is the central means through which the principle of inclusion is put into action within an education system" (UNESCO, 2017, p.22). Recent research studies on equity and equal opportunities within education (Stainback and Stainback, 2007; Azorín and Sandoval, 2019; De Haro et al., 2019; Gortázar, 2019; Muntaner-Guasp et al., 2022), have revealed the profound injustice that a single, homogeneous and standardised response to diversity represents from an educational perspective. Nevertheless, the Spanish education system continues to be beholden to a logic whereby all the students must learn the same things, in the same way and at the same time. Even though some progress has been made regarding certain aspects, the reflection made years ago by Arnáiz (1999) on the need to question the merely instructional design and the conception of the curriculum if attention to diversity is to be promoted is still valid.

This idea has been already reflected in the Incheon Declaration and Framework for Action for the development of Sustainable Development Goal 4: Ensure inclusive and equitable quality education and promote lifelong learning opportunities for all (UNESCO, 2015 a,b). This implies a shift in the paradigm as it considers that education will only be quality education as long as it embraces an inclusive approach (Alba, 2019). This premise is at the heart of this proposal, and is embodied in three core ideas (Bolívar, 2019; Muntaner-Guasp et al., 2022) as follows:

1. Education is a right for everyone without exception, and diversity is a reality that is naturally present in every person because of the multitude of traits that make us unique, valuable and unrepeatable.
2. Uniformity in the face of diversity is an unfair approach in itself; fair education entails the provision of equitable learning opportunities for all learners, i.e. offering each student what is best suited to his or her circumstances, needs, interests and talents.
3. Curricula must be viewed as a mediator between students and their learning process, thereby maximising their capacity to make progress consistent with the following main conception: we intend to educate citizens within a community and for the society.

Each of these core ideas connects respectively with three fundamental principles that have been identified by Ainscow and Booth (2006, 2015) as the basis for the development of more inclusive educational systems: presence, participation and progress of all the students. It is on these basis that Muntaner-Guasp et al. (2022) find the necessary resources for the evaluation of curricular proposals, by identifying and removing the barriers that compromise any of these principles and, consequently, inclusiveness. This implies a change of perspective from the problem-student to the problem-context (Benítez-Gaviray Aguilar-Gavira, 2022) in order to promote the implementation of facilitators or levers that modify the environment to ensure and augment student success (Azorín and Sandoval, 2019).

Our research seeks to provide answers to the following questions:

• Does the formal, government-prescribed curricula ensure equal opportunities and any progression towards more inclusive school?
• Does the implementation of the curricula in the classroom ensure the presence, participation and progress of all the students?
• What should be taught, how should it be taught and how should it be evaluated?

The general aim of this research is to analyse and characterise the impact of a curriculum as an exclusion/inclusion factor of educational systems. Although our approach is eminently qualitative, we have also considered the use of opinion surveys for descriptive purposes. As a result, with regard to certain groups of respondents the design of our research is conformed by a multi-method or mixed approach, even if it does so from an paradigmatic perspective (Maxwell 2010, 2016). Thus, our research design contemplates the gathering of information through: interviews to policy makers within the Education Administration, focus groups comprising teachers from different educational stages and opinion surveys to students. In order to identify the key aspects that should allow us to define the theoretical framework, as well as to ascertain the main aspects to be investigated on this topic, a number of experts will be interviewed as an initial exploration. Numerous studies have made use of a panel of experts as a technique to validate the data collection tools to be employed (Herrera et al., 2017; López et al., 2017). The interviews should also allow us to get to know the views of specific individuals who, because of their qualification and/or professional background, are in a position to deliver evidences and critical evaluations on the subject to be studied, while seeking rational consensus and conferring validity to the subject matter (Escobar-Pérez and Cuervo-Martínez, 2008; Robles and Rojas, 2015). This communication presents the results of the exploratory research, which was developed through in-depth interviews to 5 recognized Spanish academic researchers, who are experts in inclusive education and have extensive experience in national and international research, with a large number of publications. The five interviews have been centred on two main dimensions and core themes. Dimension A: the sense of curricula; a.1) definition of curriculum, a.2) purpose; and Dimension B: the role of curricula in inclusive education; b.1) inclusive school, b.2) curricular barriers and levers to inclusion, and b.3) inclusive curricula. The interview transcripts have been submitted to the experts for them to validate their content. The gathered information was analysed and interpreted by categorising and triangulating the data by means of the software application NVIVO. The descriptors that have been previously mentioned constituted our predefined categories and the data collected from the experts were also used to construct the emerging categories.

The main results from this initial investigation revealed some obstacles to overcome, as well as a number of elements to be taken into consideration in relation to curricula as facilitators in inclusive education contexts. These results were also in line with the recommendations made by a number of experts to the Spanish Ministry of Education with regard to the recent amendments to Spanish education law (MEFP, 2020). Some of the main obstacles found were: curricula that are markedly academic, standardised, increasingly fragmented into disciplines, and largely propaedeutic; predominance of one-size-fits-all methodologies anchored to textbooks, that promotes individuality and competitiveness, and that operate on the basis of ranking and segregating evaluative practices; curricular obstacles that validate and aggravate social, cultural and economic inequalities, thereby questioning equal opportunities and turning curricula into instruments to exclude the most vulnerable students from the education system. As opposed to this model, we propose inclusive curricula: open, flexible, up-to-date, meaningful, interdisciplinary, relevant, pertinent, sustainable and ethical. These are to be implemented through active and participative teaching and following methodological strategies that promote cooperative, dialogic and critical learning. Furthermore, they must be supported by evaluation processes that include co-evaluation and self-evaluation that aim to improve the learning process. All of this requires of teacher training, pedagogical leadership and of a novel professional teaching culture based on the collaborative work of teachers, the support from staff and families and from the rest of the education community. School improvement movements, comprising a variety of pedagogical currents and movements that support innovative approaches to education and evaluation, share the fundamental idea that the quality of education systems and institutions is brought into question when the opportunities and benefits of a "good education" do not reach all.

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