Although inclusive education has become internationally pervasive, how we understand what inclusive education is still remains ambiguous. Some authors recognizing plethora of different conceptions of inclusive education suggested that we talk about different inclusions rather than inclusion (Dyson, 1999). These ambiguity in understanding of inclusive education produced different tensions and dilemmas that have to be addressed and resolved (Norwich, 2013). One of these is a tension between equity on the one and quality of education on the other side. This debate is reflected through the question can we include students with special educational needs (SEN) and from disadvantaged socio-cultural and economic backgrounds and at the same time rise achievement of all students or how to mediate the tension between demands for excellence in academic achievements with the principle of equity (Black–Hawkins, Florian, & Rouse, 2016).

The underlying assumption of this debate is that inclusive education is zero-sum situation. Namely, in the case of restricted resources (e.g. material resources, available support, teacher’s attention), it is often perceived that gains of one person or a group are always at cost of other person or a group (Biernat & Vescio, 2002). Perception of inclusive education as zero-some leads to the question: “If someone has to lose, who should it be?” The answer usually implicates that needs of the majority should be given priority over those of the minority, under the argument of striving for quality.

This debate initiated a line of research focusing on effects inclusion of children who need additional support in mainstream schools has on academic, social and emotional outcomes of their peers (for overview, Salend & Garrick Duhaney, 1999). The findings of these research converge to the conclusion that inclusion of children who need additional support do not affect negatively quality of education their peers receive. Moreover, as a response to increasing demands for higher standards and accountability for all children, development of national datasets was intensified recently, enabling large-scale research on debate equity versus quality. Using national datasets, recent research conducted mainly in developed countries, support conclusion that high levels of equity can be compatible with high levels of quality assessed as national test achievements (Dyson, 2004; Black–Hawkins et al., 2016).

Taking into account contextual sensitivity of the inclusive education, some authors pose question of generalizability of research findings emerged in one national educational context (Engelbrecht, 2006). As Mitchell notes (2010), despite the internationalisation of the inclusive education, for a range of historical, cultural, social and financial reasons its implementation has been uneven across the world. It imposes the need for empirical verification of our assumptions in different educational contexts, especially in developing countries  where resources are limited. Moreover, although approach to exploration of inclusive education often was about development of systems (e.g. Dyson, 2010) and the development of individuals within these systems (e.g. Forlin, 1995), it seems that interaction of factors operating at different levels have often been overlooked (Skidmore, 2004).

The main goal of the study was to determine whether any statistically significant differences in success of classes with and without children who receive education under the education plan (IEP) exist. In order to answer this question we used the data obtained in national testing and singled out the schools (n=123) which have at least one class where IEP is introduced and at least one class without IEP. With the goal of obtaining a more accurate comparison, results of children with IEP were excluded from the calculation of class averages. Having in mind the nested data design (classes within schools, schools within municipalities) we decided to apply hierarchical multilevel modelling. This approach to analysis also enabled us to explore potential influence of factors from different hierarchical level (class, school and municipality), which we expected to be relevant considering the complexity of the phenomenon. However, we have not found any previous studies on this topic that simultaneously explored factors from different level. Data that was used was obtained by Ministry of Education through nationwide standardised testing, conducted in controlled conditions. The variables we had at our disposal were number of children per class, gender structure of children, number of teachers and professional pedagogical advisers, number of points they received during their training programs, their length of service in school and characteristics of municipalities (such as degree of development, employment rate, average earnings etc.).

High intra-class correlations between classes’ achievements within schools (r=.76) and moderate intra-class correlations at the municipality level (r=.45) suggested that three level analysis was appropriate. Findings suggested that there are no significant differences (β=.05, t(336)=.169, p=.866) between achievement of classes with students educated according to IEP and classes with students educated exclusively according to the regular curriculum. Also, we have discovered significant interaction between class size and degree of development of the respective municipality (β=.01, t(336)=1.979, p=.048). In the next step, we created subsample of schools (n=61) which have, in the final grade, at least one class attended by students educated according to IEP with modified standards and at least one class attended only by students educated according to the regular curriculum. In this subsample, results indicated absence of statistically significant difference in achievement on national exam between classes attended by IEP2 students and classes educated according to the regular curriculum (β=.771, t(159)=1.812, p=.071). The evidence presented here strongly supports the view that inclusion of students who need additional support in regular classes does not have a negative impact on achievements of their peers. It seems that inclusive education could be win-win situation for all.

Biernat, M., & Vescio, T. K. (2002). She Swings, She Hits, She’s Great, She’s Benched: Implications of Gender-Based Shifting Standards for Judgment and Behavior. Personality and Social Psychology Bulletin, 28, 66-77. Black-Hawkins, K., Florian, L. & Rouse, M. (2016). Achievement and Inclusion in Schools. New York: Routledge. Dyson, A. (1999). Inclusion and inclusions: Theories and discourses in inclusive education. In Daniels, H., & P. Garner (Eds.), Inclusive Education (pp. 36-53). London: Kogan Page. Dyson, A., Farrell, P., Polat, F., Hutcheson, G. and Gallannaugh, F. (2004). Inclusion and Student Achievement (Research Report RR578). Nottingham: DfES. Dyson, A. (2010). Developing Inclusive Schools: Three Perspectives from England. Die Deutsche Schule, 102 (2/2010), 115-129. Engelbrecht, P. (2006). The implementation of inclusive education in South Africa after ten years of democracy. European Journal of Psychology of Education, 21, 253–264. Forlin, C. (1995). Educators' beliefs about inclusive practices in Western Australia. British Journal of Special Education, 22, 179–185. Mitchell, D. (2010). Education that Fits: Review of international trends in the education of students with special educational needs. Christchurch: University of Canterbury. Norwich, B. (2013). Addressing tensions and dilemmas in inclusive education: Living with uncertainty. London: Routledge.