Theoretical background and research questions

With the ratification of the UN Convention on the Rights of Persons with Disabilities, which came into effect in many European countries in the late 2000s, inclusion has become a central issue in international education policy. The obligation to design inclusive education systems presents complex challenges for educational institutions, especially schools.

A key factor in the success of school inclusion is the collaboration between regular school teachers and special education teachers (Holmqvist & Lelinge, 2021). The task of creating effective learning environments for a highly heterogeneous group of pupils can only be accomplished through teamwork. Since neither regular nor special education teachers alone possess all the necessary skills to meet the demands of inclusive education, both professional groups must jointly develop new forms of teaching practice (Friend et al., 2010). In this context, school leaders play a central role as change agents. On the one hand, they can indirectly create an environment that fosters collaboration, while on the other hand, they can directly influence teacher collaboration through their interactions (Wunderer, 2003).

Inclusion places new demands on teachers and thus also increases the expectations placed on school leaders (Kugelmass & Ainscow, 2004). This results in two central leadership tasks for school leaders in the context of inclusion: supporting collaborative processes and promoting lesson development (Day & Sammons, 2013). In order to meet these requirements, two leadership styles have proven to be particularly effective in school leadership research: instructional leadership and transformational leadership. The instructional leadership style is characterized by a clear focus on improving the quality of teaching. It includes targeted advice on how to optimize teachers' actions, direct support in everyday school life, and the promotion of further development. In addition to this model, the transformational leadership style is often discussed, particularly in the context of inclusion (Badstieber et al., 2018). Transformational leadership aims to promote innovation and improve quality in social systems by focusing on the identification and performance potential of members. The aim is to raise the needs, values, and motives of employees to a higher level in order to achieve common goals (Day & Sammons, 2013).

Although interest in school leadership research has grown internationally in recent years, with general agreement on the central importance of school leaders (Louis et al., 2010), their role in the context of inclusion has not yet been sufficiently researched. In particular, there is a lack of studies that examine how school leaders influence the collaborative processes within the teaching staff that are necessary for inclusion. Although studies such as those by Lambrecht et al. (2022), Pietsch et al. (2016), or Honingh & Hooge (2014) show that school leaders can significantly influence the collaboration between teachers through their actions, the majority of these studies refer to general school settings without specifically addressing the requirements and dynamics of inclusive schools. Therefore, this research project aims to examine the perception of leadership actions from the teacher’s perspective and explore the extent to which school leaders influence the collaborative activities of teachers. To address this, the study focuses on the following research questions:

1. How intensively do teachers collaborate in inclusive primary and comprehensive schools?
2. How do teachers perceive school leadership practices?
3. To what extent do the school leadership practices perceived by teachers influence their collaborative activities?

Participants and Procedure This quantitative cross-sectional study involves a questionnaire survey with teachers at inclusive primary and comprehensive schools in North Rhine-Westphalia, Germany. Using an online questionnaire, teachers were asked about their (a) collaboration activity and their (b) perception of the school leader's actions. To date, data collection has been completed at 11 schools (N = 279 teachers), consisting of 26 special education teachers and 209 regular teachers. The planned final sample includes 30 to 35 schools. Instruments Collaboration activity (a) was measured using three scales: Exchange (α = .79), Instructional Collaboration (α = .84), and Concept Development (α = .65). The scales consist of three to five items, such as "I exchange with colleagues about particularly enjoyable or unpleasant lessons" for Exchange, "I plan joint teaching units with colleagues, and we discuss who will teach which lesson and handle differentiations" for Instructional Collaboration, and "I discuss procedures with colleagues in which each teacher individually evaluates her/his lessons and, if necessary, derives and implements actions" for Concept Development. The scales are based on those of Stommel et al. (2014), but have been adapted and modified for this study. Factor analysis revealed an acceptable model fit, with a Comparative Fit Index (CFI) of 0.94 and a Root Mean Square Error of Approximation (RMSEA) of 0.09. The assessment of school leadership behavior (b) was measured with adapted scales from Urton and Wilbert (2017), originally designed for school leaders but modified to capture teachers' perceptions of leadership in inclusive settings. The scales on school leadership behavior capture the leadership styles outlined in the theory section: instructional leadership (α = 0.95) and transformational leadership (α = 0.93). Each scale comprises four items, such as "The school leader ensures a high quality of inclusive teaching" for instructional leadership and "The school leader brings in new ideas and innovations to advance the inclusive development of the schools" for transformational leadership. Responses were recorded on a 7-point Likert scale, with options ranging from "never" to "often" for collaboration activity and "does not apply" to "fully applies" for school leadership actions.

Preliminary results (N = 11 schools) show that, consistent with findings from previous studies (e.g., Richter & Pant, 2016; Stommel et al., 2014), exchange is the most common form of collaboration (M = 5.7, SD = 1.08). Instructional collaboration occurs occasionally to frequently (M = 4.7, SD = 1.6), while the development of concepts rarely takes place cooperatively (M = 2.5, SD = 1.35). Regarding the second research question, teachers generally rated instructional leadership (M = 3.9, SD = 1.86) and transformational leadership (M = 4.7, SD = 1.75) as moderate, with slightly higher approval for transformational leadership. Additionally, preliminary results show strong correlations between both leadership types and instructional collaboration, with the highest correlation between transformational leadership and instructional collaboration (r = .49, p < .001). Medium to low correlations were observed between both leadership types and concept development (r = .21, p < .01 and r = .28, p < .01). Given the nested data structure, further data collection is planned in approximately 20 schools. The subsequent analysis will utilize hierarchical models to examine the influence of school leadership on teachers' collaboration activities. In particular, the hypothesis that school leaders provide intensive support for teachers in lesson development will be tested. This approach will also help identify potential differences between schools. Understanding these variations will offer deeper insights into how school leadership practices shape collaboration among teachers in different contexts.

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