Title Participants "Exploring the interrelationship between Universal Design for Learning (UDL) and Differentiated Instruction (DI) : a systematic review" "Júlia Griful-Freixenet, Katrien Struyven, Wendelien Vantieghem, Esther Gheyssens" "Exploring pre-service teachers’ beliefs and practices about two inclusive frameworks: Universal Design for Learning and differentiated instruction" "Julia Griful-Freixenet, Katrien STRUYVEN, Wendelien Vantieghem" "The interrelationship between UDL and DI has long been a topic of debate. This empirical study of pre service teachers has been carried out to explore underlying beliefs and practices about these two inclusive frameworks and to tap into their potential interrelationship. The results show that UDL and DI practices are different but highly interrelated. Both practices share important predictors (i.e., ongoing assessment, self-efficacy, self-regulation and motivation). However, flexible grouping was found to be a predictor of UDL only. Overall, UDL and DI are perceived as two complementary approaches with sufficient internal consistency to be integrated. (c) 2021 Elsevier Ltd. All rights reserved." "Variables that influence teachers' practice of differentiated instruction in Chinese classrooms: A study from teachers' perspectives" "Meijie Bi, Katrien STRUYVEN, Chang Zhu" "As the diversity of students increases, differentiated instruction (DI) serves an increasingly significant function in meeting their individual learning needs. Emerging research has highlighted the value of inclusive teaching approaches to address students' differences, such as DI. Therefore, it is important to quantify teachers' DI thoughts and behaviors in classroom teaching. This study follows the original Differentiated Instruction Questionnaire (DI-Quest) to investigate the factors that influence teachers' practice of DI, taking into account their teaching experience, class sizes and school locations. The sample comprised 1,935 teachers from 150 national lower secondary schools in six provinces of central and western mainland China. Exploratory factor analysis (EFA), confirmatory factor analysis (CFA), scale reliability, and invariance testing were conducted to explore and verify the factor structure of a Chinese mainland version of the DI-Quest (CN-DI-Quest). The empirical findings indicate that CN-DI-Quest is a valid and reliable instrument for future study of teachers' DI philosophies, principles, and practice. Moreover, the results of structural equation modeling revealed that teachers' practice of DI (i.e., adaptive teaching) was explained largely by their ethical compass, flexible grouping, output = input, teaching experiences, and class size. Notably, teachers' practice of DI (i.e., adaptive teaching) could not be predicted by growth mindset and school location. This study addresses gaps in the literature, since it provides empirical evidence regarding DI in Chinese mainland schools, offers material and suggestions for future research, and provides recommendations useful to the professional advancement of Chinese teachers, including training programs and professional support." "Differentiated instruction in practice: do teachers walk the talk?" "E Gheyssens, E Consuegra, S Vansambrouck, N Engels, Katrien STRUYVEN" "Differentiated instruction (DI) is put forward as a pedagogical approach to create an inclusive classroom and is considered both a teaching philosophy and a teaching praxis. DI requires that teachers adapt their teaching to students' interests, readiness and learning profiles by adopting differentiated practices such as flexible grouping and ongoing assessment. However, several studies report implementation challenges for DI practices. Using mixed methods, this study explores to what degree differentiated practices are implemented by primary school teachers in Flanders (Belgium). Data were gathered by means of three different methods, which are compared: teachers' self-reported questionnaires (N=513), observed classroom practices and recall interviews with 14 teachers. The results reveal that there is not always congruence between the observed and self-reported practices. Moreover, the study seeks to understand what encourages or discourages teachers to implement DI practices. It turns out that concerns about the impact on students and school policy are referred to by teachers as impediments when it comes to adopting differentiated practices in classrooms." "Good Things Come to Those Who Wait: The Importance of Professional Development for the Implementation of Differentiated Instruction" "Esther Gheyssens, Els Consuegra, Nadine Engels, Katrien STRUYVEN" "Differentiated Instruction (DI) is proposed as an approach to create inclusive classrooms. Research shows that professional development is necessary for teachers to implement DI efficiently. This study investigates the effectiveness of a professional development programme (PDP) aimed at strengthening the DI competences of teachers. A quasi-experimental design consisting of a pre-test, post-test and control group was used to study the impact of the programme on teachers' self-reported differentiated philosophies and practices. Questionnaires were collected from the experimental group (n = 284) and the control group (n = 80). Pre-and post-test results were compared using a repeated measure, ANOVA. Additionally, interviews with a purposive sample of teachers (n = 8) were conducted to explore teachers' experiences of the PDP. The results show that the PDP was not effective in changing teachers' DI competences. Multiple explanations are presented for the lack of improvement such as treatment fidelity, the limitations of instruments and the necessary time investment that change requires. The significance of this study lies in the bridge between the quantitative and qualitative results of the PDP. Moreover, this study exposes the complexity of research on professional development." "Differentiated instruction implementation in primary schools : linking psychological factors in students and teachers to achievement" "Muhamad Nanang Suprayogi" "Faculty of Psychology and Educational Sciences" "Student diversity has becomes the norm in today’s classrooms (Subban, 2006). This trend can also be observed in Indonesian schools (Hamdan & Mattarima, 2012). Learners mirror a large variety in differences; e.g. learner interests, abilities, learning speed, learning styles, developmental level, language level, ability level, attitudes, cultural background, etc. (Moore, 2005; Tomlinson, 2001). The traditional one-size-fits-all instructional strategy – building on single teaching strategy – neglects these student characteristics, and differences in student needs (Fox & Hoffman, 2011). The key solution is to adopt teaching strategies that cater for student diversity (Heacox, 2012; Subban, 2006; Tomlinson, 2014) since all learners deserve good education to achieve optimum learning outcomes (Yun, 2007). Quality of education in Indonesia, the context of the studies discussed in this PhD, faces clear challenges. One major challenge is related to the low academic achievement of learners as reflected in international reports about student achievement (Mullis, Martin, Foy, & Arora, 2012; OECD, 2016a, 2016b; Pearson, 2014). Another is related to low teaching quality (Raihani, 2007; Sofo, Fitzgerald, & Jawas, 2012; Sumintono & Raihani, 2010; Sumintono & Subekti, 2014; Zulfikar, 2009). Thirdly, we observe a gap between public and private schools that is reflected in the allocation of funding (Heyneman & Stern, 2014; Stern & Smith, 2016), academic achievement (Newhouse & Beegle, 2006; PUSPENDIK, 2015), salary levels of teachers, teacher motivation (DeRee, Muralidharan, Pradhan, & Rogers, 2015), the number of certified teachers and the level of access to teacher professional development (Künkler & Lerner, 2016). To deal with diverse students as well as to improve the academic achievement, many authors suggest to apply Differentiated Instruction (DI) (Fox & Hoffman, 2011; Subban, 2006; Tomlinson, 2014). DI is instructional approach emphasizing that every student is unique, inherently different, and learns in a different way (Fogarty & Pete, 2011; Tomlinson, 1995), offering students a more responsive and personalized learning experience (Fox & Hoffman, 2011), as well as engaging them in activities that better respond to their particular learning needs, strengths, and preferences (Heacox, 2012). DI implementation incorporates the psychological factors of teachers, such as teacher self-efficacy (Dixon, Yssel, McConnell, & Hardin, 2014; Wan, 2015; Wertheim & Leyser, 2002), and teaching beliefs (Cross, 2009; He & Levin, 2008; Valcke, Sang, Rots, & Hermans, 2010). It also involves other related factors such teaching experience (Donnell & Gettinger, 2015; Hargreaves, 2005), professional development (Dixon et al., 2014; Donnell & Gettinger, 2015; Rienties, Brouwer, & Lygo-Baker, 2013), teacher certification, and classroom characteristics (Subban, 2006). Differentiated instruction receives diverse labels such as ‘differentiated assessment’, ‘inclusion’, ‘student-centered’ (Fox & Hoffman, 2011), ‘individualized instruction’ (Hattie, 2009), ‘adaptive instruction’, ‘personalized learning’ (Waxman, Alford, & Brown, 2013), ‘response to intervention’ (Fox & Hoffman, 2011), and ‘Universal Design of Learning’ (UDL) (Hall, Strangman, & Meyer, 2014). Those different labels share the same idea. This is why we put forward the following general DI definition for this PhD: Differentiated instruction is an instructional approach that accommodates the diversity of students by (1) coping with student diversity, (2) adopting specific teaching strategies, (3) invoking a variety in learning activities, (4) monitoring individual student need, and (5) pursuing optimal learning outcomes. Meanwhile, DI is also approaches in different ways, which consequently implies that choices have to be made. This pushes us to define a particular implementation definition of DI. Firstly, we opt for grouping as a key design feature of a specific DI intervention. Secondly, we opt for “math ability” grouping. Next, we choose specific supporting strategies that foster cognitive processing approach (exercising math) and metacognitive processing. Lastly we provide individual and peer support that gives timely feedback in line with student capabilities. These choices help in presenting a more operational definition of DI. This DI approach – in the context of this PhD - has been studied via an intervention set up in Indonesian primary schools: Differentiated instruction is an instructional approach accommodating the diversity of students by (1) coping with student diversity in math ability levels, (2) adopting specific teaching strategies; ability grouping, (3) invoking a variety of mathematics learning experience by presenting lots of exercising possibilities; (4) monitoring individual student needs; follow-up and feedback by peers/teacher, (5) pursuing optimal learning outcomes; controlling of the time distance between instruction and exercising of the new content with or without metacognitive support. Weaker ability students will get faster instructional opportunities and feedback. Since the literature suggest that psychological factors play an important role in learners and how these factors affect achievement (Aronson, 2002; Neroni, Gijselaers, Kirschner, & Groot, 2015), , we also look in the context of this dissertation at the psychological factors: self-efficacy, motivation, and anxiety related to mathematics as psychological factors in learners. Above we gave a brief summary of research context and conceptual framework of the dissertation that have been extensively explained in the first six chapters of this dissertation. In the next paragraphs we further discuss the research objectives of this dissertation and how the research studies are linked to the research objectives. Research objectives Research objective 1. To explore the nature and the extent of DI implementation in Indonesian school. The first research objective dealt with the actual implementation of DI by teachers in their daily teaching and learning activities. The study examined two aspects: (1) the nature and (2) the extent of DI implementation in Indonesian schools. Furthermore, the study also examined potential differences in the DI implementation between public and private schools. Research objective 2. To examine the relationship between teachers’ DI self-efficacy and teaching beliefs and other related factors to the DI implementation in Indonesian School. The second research objective was to assess DI implementation and how this was related to teachers’ psychological and other factors. In this study, we mainly focused on two psychological teacher factors; i.e. teacher DI self-efficacy, and teaching beliefs. The other factors are linked teacher experience and teaching certification and two school level factors: professional development and classroom size. Research objective 3. To investigate the impact of DI intervention on the student achievement. The third research objective was to examine the impact of a DI intervention on student achievement. The DI intervention adopted in the study built on grouping and metacognitive instruction. The study took into account psychological factors of the students, i.e. math motivation, math efficacy, and math anxiety. Research objective 4. To investigate the effectiveness of DI intervention in helping struggling learners. Our fourth research objective dealt with the effectiveness of DI intervention in helping more in particular struggling learners. The study involved three different ability groups based on their mathematics capabilities, i.e. low ability, medium ability, and high ability. We considered the low ability group as the struggling learners. Overview of the chapters presented in this dissertation Chapter 2: Differentiated instruction in primary schools: Implementation and challenges in Indonesia. The study was based on a teacher survey, administered to a sample of 604 Indonesian primary schools in the most populated province, Jakarta. Both qualitative and quantitative analyses were carried out to assess the nature and the extent of DI implementation. We focused on five DI-dimensions, following our general DI definition. The results show that the nature of actual DI implementation in these Indonesian primary schools is varied. Considering the first dimension, coping with student diversity, most teachers feel realistic, as they want their students to succeed. They adopt appropriate teaching strategies. In view of the second dimension, adopting specific teaching strategies, the teachers mainly opt for grouping students in their teaching and learning activities. Furthermore, they do not agree with the one-size-fits-all (OSFA) strategy. They explicitly state this OSFA cannot accommodate student diversity. Related to the third dimension, invoking a variety in learning activities, the teachers help students being active in the class in view of comprehension of what is to be learned. Most teachers agree on the need to select different learning activities for different students. In relation to the fourth DI dimension, monitoring individual student needs, the majority of teachers agree to monitor individual students as a key responsibility of a teacher. They try to understand the nature of specific student characteristics and needs. The fifth DI dimension, pursuing optimal learning outcomes, pushes teachers to opt for active learning, to motivate students and to give extra time for remedial and enrichment activities, following the needs of a student. Studying the extent of DI implementation, we observed a DI implementation index score of 7.31/10. The score seems high. But it is lower compared to the benchmark of mastery learning (Zimmerman & Dibenedetto, 2008) of 80%. This finding reflects the need for Indonesian teachers to improve their DI implementation. None of the five DI decision dimensions (see definition) reflects scores that are at par with the benchmark. The fact that the DI implementation in Indonesia is below par, stresses the need to invest heavily in teacher professional development and to pay attention to a reorientation in Indonesian teacher education. Chapter 3: The implementation of differentiated instruction in Indonesia: A comparison between public and private schools This study was based on data from 294 public primary school teachers, and 310 private school teachers. The analysis results revealed – as expected - a significant gap between both types of school. The public school teachers reported a significantly higher extent of DI implementation than their counterparts in private schools. The significant difference is observed in some major decision dimensions in DI: dimension 1, coping with student diversity; dimension 4, monitoring individual students need; and dimension 5, pursuing optimal learning outcome. These particular findings reiterate the gaps – already reported in the literature – in the quality of public and private school as reflected e.g., in operational funds (Heyneman & Stern, 2014), and student performance (Newhouse & Beegle, 2006; PUSPENDIK, 2015), salary levels of teachers and teacher motivation (DeRee et al., 2015), the number of certified teachers and the level of access to teacher professional development (Künkler & Lerner, 2016). Our findings corroborate the need to equally support both types of schools, as all students deserve optimal quality in teaching and learning (Yun, 2007). Moreover, the privileges of public schools result in an imbalance in the quality of education in Indonesia (Heyneman & Stern, 2014). Chapter 4: Teacher and their implementation of differentiated instruction in the classroom The results of this study show a significant and positive relationship between all variables (DI self-efficacy, teaching beliefs, teaching experience, teacher certification, professional development, classroom size) and the level of DI implementation. DI self-efficacy seems to contribute significantly and strongly to the level of DI implementation, but the association of constructivist teaching beliefs remains low. Moreover, the traditional management teaching beliefs seem not significantly associated. Our findings mainly support the importance of teachers’ self-efficacy as a predictor of changes in DI practices in primary school teachers (De Neve, Devos, & Tuytens, 2015), and teachers’ intention to frequently adopt DI practices (Wertheim & Leyser, 2002). On the other hand, our assumptions as to the linkage between teaching beliefs and DI adoption are hardly confirmed. It might be because in this study, we did not let our teachers focus on a specific content domain when studying their teaching beliefs. The literature in relation to beliefs often stresses that beliefs should be contextualized (Pajares, 1992). Next, we also observed no significant contribution of teaching experience, teacher certification, and teacher professional development to teacher’s level of DI implementation. But, the contextual factor “classroom size” was significantly linked. This finding implies that the bigger the classroom, the higher the need to implement DI to accommodate student diversity (Subban, 2006; Tomlinson et al., 2003). The results in relation to teacher experience are not surprising. Donnell and Gettinger (2015) also found no significant relationship between teaching experience and adoption of innovative teaching practices. Our sampling framework could have been the cause, by including a disproportional large number of teachers with a particular experience level. Also, the relationship between experience and adoption of innovations is not always linear: more experience – higher adoption (Hargreaves, 2005). The insignificant relation between PD and DI implementation is striking. This might be related to the nature of the PD content, the teachers reported no explicit focus on DI. Another reason might be related to the lack of PD that is relevant for the real classroom context as also raised by Luschei and Zubaidah (2012). Also, we can link this to the still predominant central policy influences in Indonesian education. Teachers still rely heavily on the directives of central authorities and - though teacher and school autonomy is increasing - hardly make use of local autonomy to implement local practices and policies (Bjork, 2005). Chapter 5: The impact of differentiated instruction on student achievement: Grouping and metacognitive support as key design variables This chapter is based on the quasi-experimental study involving 223 students, assigned to 3 research conditions: 59 students in a grouping, 53 students in a grouping + MCI, and 111 students in a control condition. The study analyzed the differential impact of the DI-intervention approaches on math learning performance. Analysis of research result revealed that DI-grouping had a significant differential and positive impact on math performance. Learners in this condition outperformed learners in the two other conditions. Surprisingly, learners in the grouping + MCI condition performed significantly worse than those in the grouping condition and not significantly different from learners in the control group. The impact of DI-grouping corroborates the findings reported in the literature; especially when looking at implementations in the mathematics domain (Lou, 2013; McQuarrie & McRae, 2010). These results confirm our theoretical expectations about the impact of the ZPD in comparable ability group settings. Teachers seem to be better able to accommodate the level of learners when tackling exercises when student diversity is manageable and the distance between the current level and the next development level is somewhat smaller in a group of learners being supported at the same time. Next, the fact the DI grouping + MCI intervention did not produce the expected outcomes, is surprising. Reasons to explain this are found in the fact that MCI needs time to have an impact (see Gourgey, 1998), it requires extra cognitive resources that already is being used to tackle new math learning content, and it requires extra time and effort (Schwartz et al., 2009). Math efficacy had a significant impact on math achievement. However, math anxiety, and math motivation had no significant impact. We refer in this context to the integration of the intervention in the regular classroom activities. The intervention was set up during two of the four math lessons in the same week. This implies that students still experienced the “traditional” math instructional approach during the non-DI lessons. This might have caused inconsistencies in learner experiences and introduced uncontrolled bias in the study. In addition, the DI intervention was only integrated in the math lessons and not in language learning lessons, science classes, physical education, etc. Research shows that conditions for successful innovations or change often depend on the scale of the innovation and the extent to which the innovation is sufficiently comprehensive and school-wide. Chapter 6: Helping struggling learners: Evaluating the implementation of differentiated instruction. The study involved 69 low ability learners, 81 medium ability learners, and 73 high ability learners. The findings of this last study showed that the DI intervention seems beneficial for all students. When looking at the significant differential positive impact of grouping, all learners of different ability levels appeared to have gained academically. This reiterates the findings of Hanushek, Kain, Markman, and Rivkin (2003), who also found that group interactions and peer influences are beneficial for the full range of learner abilities. It appears that supporting learners in their Zone of Proximate Development works for all ability levels. Nevertheless, our results also showed that high ability learners keep outperforming the other ability groups. But, especially when taking initial math performance into account, the impact of the DI intervention is not always linear. It was remarkable to see that middle ability level learners reflected higher scores as compared to low and high ability learners in the grouping + MCI condition. Though this DI intervention did not result in significantly higher math performance, compared to learners in the control condition, it was nevertheless worth noting how middle ability level learners reacted differently to the MCI approach. This urges us at least to be careful in our expectations as to the “linear” impact of interventions. Montague, Krawec, Enders, and Dietz (2014) referred to this when studying the impact of cognitive strategy instruction in middle school. Implications of the findings in this dissertation Theoretical implications The results empirically link teacher DI self-efficacy and teaching beliefs to levels of DI implementation. This also strengthens theoretical models of teacher professionalism and the Onion model of Korthagen that interlinks behavior, competences and underlying factors. The findings in our DI intervention study imply that we can underpin theoretical assumptions about ability grouping and how DI reinforces the mechanisms as defined in Vygotsky’s theory about the Zone of Proximate Development (Vygotsky, 1980). Grouping and ability grouping seem to empirically ground these assumptions. Practical implications As to practical implications, the findings of the first studies (chapter 2) push the school to consider psychological factors in teachers, i.e. Self-efficacy and teaching beliefs, when developing programs for teacher education and teacher professional development (PD). Teachers should be confronted with their own teaching beliefs, their own behavior, and their own competences. This requires more in-depth, longer duration and active PD approaches. Policy implications From a policy perspective, an innovation plan should be set up that interlinks teacher professional development, teacher initial training, school support, school policy development and school monitoring. At the same time, school principals could be made accountable to map and track the teaching approaches of their teachers to cater for student diversity. School based monitoring, considering the particular school diversity, should be established and schools/principals should be empowered with tools and expertise to monitor learner and teacher progress. A collaboration with universities and teacher education institutes could be beneficial in this context to pool expertise. The fact that DI implementation in Indonesia is still below par, leads to a strong recommendation to the Indonesian educational authorities to look in-depth at teacher professional development (PD) programs in Indonesia both for pre-service teachers and for in-service teachers. Towards a comprehensive approach to implement DI in Indonesia, some grounding ideas The findings of the studies in the present PhD, our discussion of the results, an analysis of limitations and a first projection of implications are helpful to draft the outline of a more comprehensive approach to implement differentiated instruction in Indonesia. Firstly, we propose strengthening initial teacher education. The teacher education has a significant role in improving quality of teaching, and therefore the initial teacher education in teacher education institution needs to be improved. Secondly, we propose an enhancement of the quantity and quality of professional development (PD). The result of the fourth chapter in this PhD thesis revealed that 27% of the participating teachers never attended PD. This is strange and crucial, as teacher is the key player in an education setting that should receive opportunities for continuous upgrading their professional competences. The research has shown that PD has significantly improves teacher professionalism (Rienties et al., 2013), and school quality (Hoque, Alam, & Abdullah, 2011), as well as educational reforms (Barmby, Bolden, Raine, & Thompson, 2013). Therefore, educational authorities, including school principals, should empower and encourage all teachers to actively participate in PD programs. Thirdly, we want to redefine the role of the principal / school leader. School leaders significantly influence teacher motivation, commitment, and overall beliefs about their working conditions, which in turn can result in improvements in classroom level teaching and learning (Leithwood, Harris, & Hopkins, 2008). For that reason, principals and school leaders need to develop an empathic understanding of teachers and actively work to develop these capacities. Fourthly, we propose pushing collegial consultation. The success of a shared school vision depends on its responsiveness to internal and external environments, including the local community and broader context (Penlington, Kington, & Day, 2008). Also, collaboration between schools in the same district is highly recommended. The collaboration could involve teacher education institutes/universities. Authors suggest that well-developed professional learning communities have a positive impact on both teaching practice and student achievement (Vescio, Ross, & Adams, 2008). Lastly, empower a teacher certification program. The enactment of teacher certification programs by Indonesian Government aimed at improving teaching quality, and therefore improving academic outcomes (Jalal, 2009). Empowering teacher certification programs could also imply involving other stakeholders (students and parents) to enrich the supporting assessment of teacher teaching quality. The government should also set periodical assessment to guarantee the certified teachers to apply good quality teaching that results in good academic outcome. This can be a motivation for teachers to improve their skills and capabilities." "Differentiated instruction as an approach to establish effective teaching in inclusive classrooms" "Esther Gheyssens, Júlia Griful-Freixenet, Katrien Struyven" "Differentiated Instruction has been promoted as a model to create more inclusive classrooms by addressing individual learning needs and maximizing learning opportunities. Whilst differentiated instruction was originally interpreted as a set of teaching practices, theories now consider differentiated instruction rather a pedagogical model with philosophical and practical components than the simple act of differentiating. However, do teachers also consider differentiated instruction as a model of teaching? This chapter is based on a doctoral thesis that adopted differentiated instruction as an approach to establish effective teaching in inclusive classrooms. The first objective of the dissertation focused on how differentiated instruction is perceived by teachers and resulted in the DI-Quest model. This model, based on a validated questionnaire towards differentiated instruction, pinpoints different factors that explain differences in the adoption of differentiated instruction. The second objective focused on how differentiated instruction is implemented. This research consisted of four empirical studies using two samples of teachers and mixed method. The results of four empirical studies of this dissertation are discussed and put next to other studies and literature about differentiation. The conclusions highlight the importance of teachers’ philosophy when it comes to implementing differentiated instruction, the importance of perceiving and implementing differentiated instruction as a pedagogical model and the importance and complexity of professional development with regard to differentiated instruction." "Differentiated Instruction in Teaching and Teacher Education: the DI-Quest model." "Katrien STRUYVEN, Esther Gheyssens, Julia Griful-Freixenet" "Measuring teachers’ perceptions about differentiated instruction: The DI-Quest instrument and model" "Catherine Coubergs, Katrien STRUYVEN, Gert Vanthournout, Nadine Engels" "Within a democratic and multicultural society, diversity is a reality, and differences between students are a fact which teachers have to deal with on a daily basis. Differentiated instruction aims to meet these differences in learning in order to provide all students with the best possible learning opportunities. However, to date no validated instruments exist to measure teachers' perceptions of differentiated instruction and their related classroom practices. This study, therefore, examined the factor structure and reliability of the Differentiated Instruction Questionnaire, called the DI-Quest instrument. A list of 87 items was constructed, building on existing prevalent theoretical models of Differentiated Instruction (e.g. Tomlinson, 2014; Hall, 2002). An exploratory and confirmatory factor analysis was undertaken to investigate the factor structure of the questionnaire. As a result, five factors emerged: two factors related to the teachers' philosophy of differentiated instruction (the teachers' mindset and their ethical compass), two factors referred to the practical principles that teachers apply to differentiate (flexible grouping and output = input) and the last factor (differentiated instruction) covered the self-reported extent to which teachers differentiated their instruction related to three types of differences in learning (students' interests, readiness and learning profile). As a result, the DI-Quest instrument entailed 31 items with a five-factor structure indicating a good fit (CFI = 0.919; TLI = 0.911; RMSEA = 0.041 [0.037-0.044-90% confidence interval, p(0.05) = 1.000]; SRMR = 0.048; x 2 = 5888.338, df = 465, p = 0.000). In addition, assuming theoretical relatedness between the factors, the validation of a DI-Quest model was empirically validated. We compared the model fit for two models by investigating which model had a lower BIC and AIC value and by comparing their chi square values. The best-fitting DI-Quest model showed four factors (teachers' mindset, ethical compass, flexible grouping and output = input as dependent variables) functioning as significant predictors of the fifth factor (the self-reported adoption of Differentiated Instruction, which served as an independent variable). Moreover, this paper also discusses the psychometric properties of the DI-Quest instrument and the implications of the model for schools, educators and researchers." "Differentiated instruction: the diversity of teachers' philosophy and praxis to adapt teaching to students' interests, readiness and learning profiles" "Esther Gheyssens, Catherine Coubergs, Julia Griful Freixenet, Nadine Engels, Katrien Struyven" "Differentiated instruction (DI) addresses academic diversity in order to maximise learning. Although it is theorised as both a philosophy and as a praxis of teaching, it is rarely measured as such. This study examines teacher profiles on differentiated instruction relating to their philosophy and self-reported praxis. The data stem from an exploratory study on differentiated instruction, which served the purpose of creating a valid instrument to measure teachers’ philosophy and teaching approaches relating to academic differences in interests, readiness and learning profiles, namely the DI-Quest instrument. The results reveal three teacher profiles based on five DI-related factors. The patterns are almost identical in primary and in secondary education. Interestingly, if more frequent adaptations to students’ differences in interests, readiness and learning profile are what differentiated instruction aims for, both philosophical factors (namely growth mindset and ethical compass oriented to students) need to be present. Lacking one of these factors, will have less adaptations as a consequence. This study displays the predictive power of teachers’ philosophy about Differentiated Instruction for their daily classroom practices. Consequences for future research, professional development and teacher education are discussed in detail."