Didi Suryadi

Developing table tennis rackets using local materials is crucial to support national sports innovation and athlete performance. This study aimed to evaluate the usability and performance of the Garuda Unesa Speed (GUS) table tennis racket developed using Makassar ebony wood veneer. The evaluation focused on three main aspects: design, functional purpose, and safety. A total of 37 respondents consisting of non-elite athletes, elite athletes, and table tennis experts participated in the trial. A comparative experimental method was used, and data were analyzed using one-way ANOVA and Tukey HSD post hoc tests. Results showed significant differences in design perception (F = 13.275, p < 0.001) and functional purpose (F = 8.642, p = 0.001), but no significant differences were found in safety aspects (F = 2.182, p = 0.128). Elite athletes consistently gave lower scores than the other groups. The GUS racket was well received by both general and expert users, particularly for its balance of design and ease of use. Although elite athletes exhibit higher performance demands, the racket meets basic usability standards and has potential for further development in a professional context. This study is unique in integrating local wood materials with a user-driven evaluation approach in racket development. Its contribution lies in demonstrating that natural material innovations can be validated for high-performance sports equipment, and supporting the advancement of sports technology research.

Combinatorics is widely regarded as difficult, yet most studies stop at classifying student errors without explaining their internal structures. This study reframed epistemological obstacles in combinatorial counting principles as praxeological gaps. Drawing on Brousseau's notion of obstacle and Chevallard's four-component praxeology (task, technique, technology, theory), it asks not where a difficulty comes from but which part of a learner's knowledge has failed to develop. Within the prospective phase of Didactical Design Research, we collected written responses to two counting problems from 83 pre-service mathematics teachers who had completed a Discrete Mathematics course, interviewed 17 of them, and read their textbooks praxeologically. Triangulating these sources, we identified three recurring gaps: a technique whose justification had collapsed into a surface keyword rule ("and" means multiply, "or" means add); a technique fitted only to familiar problems; and a technique applied with no justification at all. Across all, the practical block was secure while the theoretical block remained thin, an asymmetry mirrored in the textbook, which defined the rules through keywords rather than independence and disjointness. Reading obstacles this way turns a general diagnosis into a specific one, giving teacher educators a tool for designing instruction that targets the precise failed component of reading.

Artificial Intelligence (AI) as a representation of technological advancement, has been recognized for its potential to positively and negatively impact the educational sphere. In mathematics education, AI revolutionizes learning by offering students more flexible and adaptive learning experiences. This study aims to provide insights into the impact of AI integration in mathematics education through a systematic literature review (SLR). The primary focus of this research includes trends in AI usage based on year, country, and education level, types of AI integration, and the impacts and challenges encountered in implementing AI in mathematics learning. The research data comprises empirical articles collected using the PRISMA approach, drawing from databases such as Scopus, ERIC, and SAGE over the past five years. This results in the analysis of 13 selected articles. The findings reveal dynamic trends in AI utilization, particularly in Indonesia and Australia. In Indonesia, AI is primarily used to expand access to online education, while in Australia, it is leveraged for personalized learning. AI is predominantly integrated at the middle school and university levels, with ChatGPT as the primary tool to assist students in understanding mathematical concepts. The benefits of AI include improvements in cognitive, affective, and teaching abilities. The challenges of AI identified include low user awareness, limited educator skills, cognitive impacts on students, and technological access disparities that exacerbate educational inequalities.

Geometric transformations are one of the essential topics in mathematical learning, as they support students’ spatial reasoning, spatial visualization, and understanding of geometric relationships. Despite its importance, many students still have difficulties in interpreting transformation concepts beyond routine procedural exercises, particularly problems that are presented in unfamiliar or contextual situations. Therefore, this study aimed to explore students' learning obstacles in learning geometric transformations and examine their implications for the development of didactical design. Qualitative approach with a didactical design research framework was employed using a phenomenological perspective. Participants involved were 36 ninth-grade students and one mathematics teacher from a junior high school in West Bandung Regency, Indonesia. Research data were collected through a written test on mathematical spatial ability consisting of four contextual problems, a semi-structured interview, and a praxeological analysis of a textbook. The written-test instrument was validated by two mathematics education experts and one experienced teacher before implementation. The data were analyzed using the Miles and Huberman interactive model, involving data reduction, display, and conclusion drawing, to categorize students’ difficulties into epistemological, ontogenic, and didactical obstacles. The research revealed that students experienced interconnected categories of learning obstacles. Epistemological obstacles appeared in students’ inability to concept generalization, misconceptions of the transformations’ properties, and dependence of procedural examples. Ontogenic obstacles related to limited spatial relations ability, weak understanding of Cartesian coordinates, and difficult to interpret contextual problems. Lastly, didactical obstacles emerged from teacher-centered instructions, limited use of interactive visual media or technology, and emphasis on procedural completion compared to conceptual exploration. These obstacles interacted with one another and influenced students' understanding of geometric transformations. The study implies that effective didactical design should integrate conceptual understanding, spatial visualization, multiple representations, contextual learning, and dynamic technology to facilitate meaningful learning of geometric transformations. Keywords: learning obstacles, geometric transformation, epistemology, ontogenic, didactic.

This study examines the process of external didactic transposition in linear regression material, namely the transformation of scholarly knowledge into knowledge to be taught. This transposition is important to ensure that knowledge that is complex and tends to be abstract for students can be accessed and easily understood, especially in the context of linear regression so that it can develop students' statistical literacy. The research method was conducted with a document study by analysing primary books on statistics, reference guidelines for the preparation of mathematics textbooks, and educational curriculum documents in Indonesia. The results of the study showed that the knowledge adaptations that have been identified are the meaning of dependent and independent variables, the concept of linear regression, the concept of best fit line, linear regression equation model, and random error. Although there are knowledge adaptations that facilitate understanding for students, there are also limitations in the presentation of random error distribution assumptions in the knowledge to be taught. The contribution of this research is an understanding of the construction of statistical knowledge presented in the educational context and the strengthening of materials that can develop students' statistical literacy. Penelitian ini mengkaji proses transposisi didaktis eksternal pada materi regresi linear, yaitu transformasi pengetahuan ilmiah (scholarly knowledge) menjadi pengetahuan yang akan diajarkan (knowledge to be taught). Transposisi ini penting untuk memastikan pengetahuan yang kompleks dan cenderung abstrak bagi siswa dapat diakses dan mudah dipahami, khususnya dalam konteks regresi linear sehinga dapat mengembangkan literasi statistik siswa. Metode penelitian dilakukan dengan studi dokumen melalui analisis buku primer materi statistika, pedoman acuan penyusunan buku teks matematika, dan dokumen kurikulum pendidikan di Indonesia. Hasil studi menunjukkan adaptasi pengetahuan yang telah teridentifikasi yaitu pemaknaan variabel dependen dan independen, konsep regresi linear, konsep garis best fit, model persamaan regresi linear, serta random error. Walaupun terdapat adaptasi pengetahuan yang memfasilitasi pemahaman untuk siswa, tetapi ditemukan pula adanya keterbatasan dalam penyajian asumsi distribusi random eror dalam knowledge to be taught. Kontribusi penelitian ini yaitu pemahaman terhadap konstruksi pengetahuan statistika yang disajikan pada konteks pendidikan serta penguatan materi yang dapat mengembangkan literasi statistik siswa.

Adab, the Islamic ethical orientation governing the conduct of knowledge, functions as an operational pedagogical principle shaping Arabic language teaching in a tahfīẓ pesantren in West Java, Indonesia. Using a qualitative case study design, the research was conducted at a purposively selected institution in which Qur’anic memorization constitutes the primary educational commitment. Participants included one institutional leader, two Arabic language teachers, and fourteen students distributed across junior and senior learning groups. Data were generated through 12 structured classroom observation sessions, semi-structured individual interviews, and institutional document analysis; thematic analysis, following Braun & Clarke’s (2006) six-phase procedure, yielded three analytical themes mapped directly to the three research questions. The findings demonstrate that Adab is not merely a background value but is explicitly invoked as a principle governing real-time instructional decisions, including lesson scope, pacing calibration, and the management of cognitive demands relative to students’ memorization responsibilities. At the junior level, Adab-oriented restraint manifests through visual scaffolding, tikrār (repetition-based memorization practice), and intensive teacher mediation; at the senior level, it shapes the integration of classical grammatical traditions with analytical textual interpretation. Framed through intercultural education theory (Bennett, 1993, 2017; Byram, 1997, 2021; Holliday, 2011; Kramsch, 1993, 2021), these instructional adaptations are theorized as intercultural pedagogical alignment — teachers’ principled, culturally informed negotiation between communicative language pedagogies and the institution's memorization-centered learning culture. Three specific contributions are advanced: (1) an empirical account of Adab as documentable classroom-level practice rather than abstract norm; (2) the concept of intercultural pedagogical alignment as a new analytical category for value-oriented educational settings; and (3) a reinterpretation of the absence of Arabic immersion environments as a cognitively rational, ethically grounded institutional choice.

Background: Geometry is a fundamental branch of mathematics that develops students’ spatial reasoning, logical thinking, and problem-solving abilities. One important topic in geometry is the Pythagorean Theorem, which remains challenging for many students due to persistent conceptual and procedural difficulties in solving related problems. Aims: This study aimed to identify and analyze students’ learning obstacles in the Pythagorean Theorem from epistemological, ontogenic, and didactical perspectives through a systematic literature review. Method: This study employed a qualitative approach using a Systematic Literature Review (SLR) following the PRISMA protocol. Twenty articles published between 2019 and 2025 from 14 academic journals were selected based on predefined inclusion and exclusion criteria. The collected studies were analyzed qualitatively to identify patterns of learning obstacles and instructional challenges in learning the Pythagorean Theorem. Results: The findings revealed that students’ difficulties were predominantly associated with epistemological obstacles, including fragmented understanding of powers and roots, misconceptions regarding side relationships in right triangles, reliance on trial-and-error strategies when using Pythagorean triples, and inability to interpret the theorem as a meaningful geometric relationship. These difficulties were further reinforced by ontogenic obstacles such as limited prerequisite knowledge, weak visual–spatial reasoning, and poor problem-modeling ability. In addition, didactical obstacles emerged from instructional practices emphasizing formula memorization and procedural computation rather than conceptual reasoning, visualization, and proof. Conclusion: This study concludes that learning obstacles in the Pythagorean Theorem are multidimensional and interconnected across epistemological, ontogenic, and didactical domains. Therefore, mathematics instruction should integrate conceptual understanding, visual representation, and contextual problem-solving activities to support meaningful learning of the Pythagorean Theorem.

This study aims to explore how the difficulties of high school students in learning mathematics, especially in functional materials. The data obtained in this study were 7 out of 22 articles and theses after going through a series of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) stages with the Systematic Literature Review (SLR) approach. The articles and theses obtained came from Google Schoolar with the help of the Publish or Perish application. Based on the studies that have been analyzed, the results are obtained that students' mathematical difficulties, especially in function, are divided into three major parts, namely difficulties in the learning process, difficulties in working on problems, and internal and external difficulties. On the other hand, there is also an anticipation to reduce the occurrence of mathematical difficulties in students, including creating a supportive learning environment from the way of teaching and educating teachers, student readiness in learning, and comfortable school environments.

Digital Didactical Design Alternatif Based on Learning Obstacles in Topic of Proportion: A Study of Pre-Service Mathematics Teachers