Since the 1990s, many researchers have promoted differentiation as a means of supporting individual learners in diverse classrooms. The expectation that teachers use differentiation as part of their toolbox of strategies to create inclusive learning environments for all students is expressed in policy, curricula documents and textbooks internationally. But what is differentiation? Despite widespread use of the term and claims that teachers use it, there is evidence of confusion in understanding and inconsistency in practice. This feeds into longstanding criticisms and myths about differentiation (Wormeli, 2005). These have intensified in recent years connecting the argument that differentiation is ineffective and unrealistic to the argument that inclusive education is a failure itself. Underpinning some of these criticisms are fundamental assumptions about the nature of the differences between children and the organisation and purpose of education. The extent that the differentiation literature can respond to these criticisms is dependent on the clarity of its own position. However, it is possible that variation in the ways that differentiation is conceptualised and described in the research literature adds to the confusion.

Our initial review of the literature finds little agreement as to what differentiation is (Graham, Davis & Spandagou, forthcoming). At one end of the continuum, differentiation is described as a learning and teaching framework that underpins planning, instruction and assessment (Tomlinson, 2014), and at the other end differentiation is seen as anything different that a teacher provides to a student in a class (Levy, 2008). Differentiation as a learning and teaching framework is informed by social constructivist ideas. However, such ideas compete with psychometric theories of intelligence and ability. This is exemplified in the origins of differentiation in gifted education and special education. While it is acknowledged that differentiation originates from gifted education (Cassady et al., 2004), gifted education in its early years utilised the models of special education in terms of identification, assessment, placements and programs and categorical considerations (VanTassel-Baska, 2003). Thus both fields of education are defined by the boundaries of the identification of ‘exceptional’ student populations characterised by ‘special’ characteristics. Inclusive education, by contrast, challenges not only the utility but also the existence of such boundaries between groups of students. Most importantly, such models are based on a bell-curve understanding of ability. Such an understanding predefines individual students’ ‘potential for learning’, ‘ways of learning’ and ‘rates of learning’. Even when the focus moves from specialised provision to the mainstream or regular classroom, this is reproduced in the below average – average – above average typology, which conflates ability with attainment (Hart, 1998), and in turn is used to group students, providing access to different elements of the curriculum and tailored instructional methods and assessments. While such understandings are evident in the differentiation literature, these are not the only ones. For instance, the distinction between readiness and ability has been emphasised in Tomlinson’s (2014) more recent work. However, as we will argue in this paper, there is a paucity of literature and research on differentiation from an inclusive education orientation. This is of significance when considering the potential of differentiation in supporting the development of inclusive learning environments.

To better understand the origins and nature of this confusion, this paper presents a critical analysis of 32 studies identified through a systematic review of empirical research on differentiation (Graham, Davis & Spandagou, forthcoming). In this presentation, we present the results of this systematic review, explain the social network methodology employed in this analysis, describe the features of the research in each of the network groupings, and discuss the implications of this definitional minefield for inclusive practice and the support of students with disability.

The primary objective of this systematic review was to investigate the different ways in which differentiation is conceptualised in the education research literature. Searches were undertaken in A+ Education, Academic Search Elite, Education Source, ERIC, Proquest Education Database, Proquest Social Science Database and PsychInfo from January 1999 to February 2017 for studies with the terms ‘differentiat*’ and ‘school’ within title and abstract. The searches identified 1002 records. Removal of 545 duplicates left a total of 457 records, which were screened following PRISMA guidelines and according to explicit inclusion/exclusion criteria. More than half (50.25%) of the records excluded at this stage were not empirical. Another 40.65% of records were excluded because they were not related to school education or included only adult participants. Two-hundred and eleven (N=211) peer-reviewed, empirical full-text articles that were published in English and focusing on primary and/or secondary school education were included in the full-text screening phase, which proceeded in two stages. In stage one, articles were screened for relevance to education and teaching practice. Of the 139 articles that were excluded, 122 (87.77%) did not focus on differentiation as understood in an educational sense; for example, in 45 articles the term was used as a synonym for ‘distinguishing between’. In the second full-text screening stage, we divided the remaining 72 articles into two groups: (1) articles that conceptualised differentiation in a way that was compatible with Tomlinson’s (1995) definition, and (2) articles that did not. Articles in the latter group were also excluded, as they used the term differentiation to refer to streaming, withdrawal, and ability grouping; not the practice of teaching diverse learners in heterogeneous classrooms. The final sample comprised 32 articles that conceptualised differentiation as per Tomlinson’s (1999) definition of a flexible approach to teaching in which “the teacher plans and carries out varied approaches to the content, the process, and/or the product in anticipation of or in response to student differences in readiness, interests, and learning need” (p. 10). These 32 articles were examined to identify their disciplinary orientation resulting in three groups: those informed by gifted education, those informed by special education, and those with a general education orientation. A ‘social network’ of the 32 articles was developed to represent these groupings. In this paper, we examine similarities and differences in the conceptualisation of differentiation within and between groupings.

Our analysis shows that despite each of the 32 articles conceptualising differentiation in a way that is compatible with Tomlinson’s definition, there is still substantial variation in relation to what is being researched and, most importantly, how differentiation is operationalised. Part of this variation is due to disciplinary orientation with differences in conceptualisation from the fields of gifted education and special education, as well as the spaces between. For the majority of studies, differentiation is about how teachers understand and respond to student diversity. It is assumed that since all students are in the same context, diversity is an individual characteristic, rather than a contextually constructed one. Only a handful of the reviewed articles focus on how contextual factors impact on what needs to be differentiated, under what conditions and for whom. Further, even though some studies make references to inclusion, not one utilises an inclusive education orientation in operationalising differentiation. This, we argue, limits the potential of differentiation to challenge the actual factors that prevent the development of inclusive learning environments.

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