In future education, the aim will be to strengthen the mathematical skills of disadvantaged student groups through personalized learning approaches and universal design principles, to maximize the potential of each student and to increase their academic success by providing equal opportunities.

Mathematics education equips students with essential skills and the ability to address global challenges. An equitable approach ensures all students receive quality education. Universal Instructional Design (UID) plays a key role in this by offering flexible strategies that meet diverse needs, making abstract concepts accessible, and helping students overcome barriers to develop mathematical thinking. This article explores UID's impact on mathematics education.

The relationship between personalization of education and UID reflects the combination of educational models that aim to individualize students' learning processes by considering their individual differences. Personalized education provides learning experiences that are adapted to students' individual needs, pace, interests and strengths (Walker, 2020). This approach, instructional strategies are designed according to each student's learning pace and preferences, ensuring the student's active participation in their own learning process (Pane et al., 2015).

UID is an instructional framework that ensures that all students with different learning styles and potential disabilities have equal opportunities in education. UID provides a variety of options for students to receive, express, and participate in information by diversifying instructional methods (Meyer, Rose & Gordon, 2014). These multiple representation, expression and participation strategies are designed to adapt to the individual learning needs of each student and aim to minimize barriers to learning (CAST, 2018). When the personalization of education is supported by the flexibility and diversity offered by UID, customized learning opportunities can be created according to the different learning styles and needs of students. Within UID, personalized learning enables educational materials and teaching methods to be more accessible and effective by considering students' strengths (Rose & Dalton, 2009). This combination allows students to set individual goals and be provided with learning pathways appropriate to those goals, while supporting all students to learn with equal opportunities (Cavalcante, 2019). This design model aims to make learning experiences more accessible and effective by adapting to the individual needs of each student. The principles of UID develop different strategies for students to increase their opportunities and participation in the learning process. UID aims to ensure that all students have access to quality education without discrimination by focusing on students' brain functioning and learning processes. While UNESCO emphasizes that educational policies should address the diversity of students, it has been stated that the educational vision in our country should provide equal opportunities for all students regardless of individual differences (MoNe, 2018). Inclusive education is an approach that aims to ensure the equal participation of all individuals, regardless of disability, in mainstream education (Stubbs, 2008; UNESCO, 2005). According to this understanding, every student is part of the school community and individual differences provide an opportunity to enrich the learning process (Taylor and Sidhu, 2012).

In this context, the purpose of the study is to examine the effects of mathematics instruction on achievement, attitudes, and self-efficacy by applying the UID model to disadvantaged student groups in Şanlıurfa, one of the provinces with a high refugee potential in Turkey. It aims to investigate how UID plays a role in making mathematics learning accessible, flexible, and inclusive, considering the diversity of students, and to analyze the effects of different digital materials and teaching strategies to support learning processes and strengthen mathematical skills. How does a mathematics lesson based on UID, developed for disadvantaged groups of students at secondary level, affect students' performance in mathematics courses, their attitudes towards the course and their self-efficacy?

This research is a mixed-methods study focused on examining the teaching of mathematics to disadvantaged middle school students using Universal Instructional Design (UID) and evaluating its effects. Mixed-methods research combines both qualitative and quantitative approaches to provide a comprehensive understanding of the research issue (Creswell et al., 2003). The study used an embedded design, where quantitative data were first collected and then supported by qualitative data to provide further clarification. For the quantitative part of the research, a quasi-experimental pre-test-post-test control group model was applied, while a case study method was used for the qualitative aspect. This combined approach aims to assess the effects of UID-based lesson plans on various student characteristics related to mathematics. UID’s fundamental principles play a key role in this study. The first principle emphasizes presenting information in various formats to cater to different learning styles, using visual, auditory, and tactile materials to engage students through multiple sensory channels (Rose & Dalton, 2009). The second principle focuses on giving students the opportunity to express their learning in different ways, such as through written, verbal, graphical, or digital means, supporting individual expression and a deeper understanding of the content (CAST, 2018). The third principle is about providing flexibility in the learning process, allowing students to progress at their own pace, which enhances motivation and engagement (Meyer et al., 2014). These principles are especially helpful for students who face difficulties with abstract mathematical concepts, as they can assist in bridging gaps in understanding and connecting new knowledge to prior learning experiences. The study was conducted at a socioeconomically and socioculturally diverse secondary school in Sanliurfa, Turkey, a region with a high refugee population, during the 2024-2025 academic year. A total of 100 students were selected using a convenience sampling method. Heterogeneous classes were created based on the students’ grade point averages to ensure diverse representation in both the control and experimental groups. For data collection, an academic achievement test aligned with the mathematics curriculum was developed. Students' attitudes towards mathematics were measured using a Likert-scale attitude survey by Önal (2013), while self-efficacy in mathematics was assessed using Akgül's (2014) Mathematics Self-Efficacy Scale. The qualitative portion involved interviews and student identification forms. The lesson plans were designed for 40 lessons over eight weeks. Descriptive analysis was used for interpreting interview data, while normal distribution tests and binary correlation analyses were conducted to analyze the research hypotheses.

Universal Design-Based Mathematics Teaching is an approach that takes into account different learning styles of disadvantaged students. The possible outcomes of this teaching model aim to increase students' mathematical achievement and participation in the learning process. In line with the quantitative research culture, a significant increase in students' mathematical achievement is expected. In particular, different representations (visual, auditory, tactile) and flexible teaching methods can strengthen students' conceptual understanding. Qualitative research suggests that students' attitudes towards teaching and self-confidence may improve. In addition, improvements in students' mathematical reasoning, problem solving and critical thinking skills are expected. Reducing students' anxiety and fear of mathematics and increasing their motivation to learn are other expected outcomes.

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