Introduction

Spatial ability is a fundamental cognitive skill in learning geometry, closely linked to students’ understanding of mathematical concepts. It refers to an individual's capacity to visualize, represent, and manipulate objects in three-dimensional space (N. Muhammad et al., 2022). In the context of mathematics education, particularly geometry, spatial ability plays a crucial role in interpreting transformations, rotations, and spatial relationships among objects (A. F. N. Muhammad et al., 2019). For pre-service mathematics teachers, strong spatial skills are essential not only for comprehending geometric concepts but also for effectively communicating them to students. However, previous research has consistently shown that many pre-service teachers struggle with these skills (Adebola,2022). In particular, existing instructional approaches often overlook crucial aspects of spatial ability development, such as the use of dynamic visualization tools, the incorporation of culturally relevant contexts, and opportunities for hands-on, project-based experiences. For pre-service teachers, these gaps translate into significant challenges, including difficulty in visualizing and manipulating three-dimensional objects, limited exposure to innovative pedagogical models, and a lack of confidence in teaching geometry effectively. These issues highlight the urgent need for pedagogical interventions that can meaningfully strengthen their spatial understanding.

Geometry instruction in teacher education programs remains largely dominated by traditional methods, including textbook-based instruction, static visual representations, and lectures. These conventional approaches have proven to be insufficient in promoting deep engagement or developing students’ spatial reasoning abilities (Zhu et al., 2023). Geometrical learning, by nature, requires high levels of cognitive involvement through dynamic visualization, exploration, and the creation of geometric representations(Žakelj & Klančar, 2022). As such, there is a pressing need for more contextual, interactive, and experiential learning strategies that can foster a deeper understanding of spatial concepts.

One innovative strategy that has gained increasing attention in the past decade is Project-Based Learning (PjBL). This approach encourages students to engage in real-world, meaningful projects that demand problem-solving, collaboration, and the practical application of mathematical knowledge(Nilimaa, 2023). Within geometry instruction, PjBL enables students to develop spatial understanding through hands-on exploration and the creation of geometric products, whether physical or digital.

The effectiveness of PjBL can be further enhanced when combined with ethnomathematical approaches, which incorporate elements of local culture into the learning process(Hamimah et al., 2022). Ethnomathematics enables students to learn mathematics in a more meaningful way by connecting abstract concepts with culturally embedded practices. Architectural patterns and shapes from traditional cultures, for instance, can be used as rich contextual materials to explore geometric concepts(Gusfitriet al., 2022). IntegratingPjBLwith ethnomathematics not only enriches the learning experience but also promotes holistic education by linking mathematics to social and cultural realities. For pre-service teachers, this approach nurtures both pedagogical content knowledge and cultural responsiveness- two competencies essential for 21st-century educators.

Despite its promise, the integration of PjBL and ethnomathematics in geometry instruction remains underexplored, particularly in Indonesian teacher education contexts. Preliminary observations conducted by the research team at the private university where this study took place revealed that geometry courses are still predominantly lecture-based, with limited use of project work or culturally relevant materials. As a result, students' spatial visualization skills, especially in interpreting and constructing three-dimensional objects, remain underdeveloped.

Furthermore, studies that explore the integration of PjBL, ethnomathematics, and geometry are still limited and fragmented. Most existing research tends to focus on these components in isolation and rarely addresses their combined effect on spatial ability(Geary, 2022). Therefore, a clear research gap exists concerning how a systematic combination of PjBL and ethnomathematics in geometry instruction can influence the development of spatial abilities among pre-service mathematics teachers.

In response to these issues, this study aims to examine the impact of project-based learning integrated with ethnomathematical contexts on the spatial ability of pre-service mathematics teachers. Specifically, this study addresses two primary questions: (1) How does the implementation of ethnomathematics-based Project-Based Learning affect the improvement of spatial ability among pre-service mathematics teachers? and (2) Is there a significant effect of the integratedPjBL-ethnomathematics geometry instruction on students’ spatial abilities? By answering these questions, this research seeks to contribute both theoretically and practically to the development of effective instructional models in mathematics teacher education.

Methodology

Research Design

This study employed a quasi-experimental design using a pretest-posttest control group format. This approach was selected to evaluate the effectiveness of ethnomathematics-based Project-Based Learning (PjBL) in enhancing the spatial ability of pre-service mathematics teachers. The experimental group received instructional treatment using PjBL with ethnomathematical integration, while the control group followed conventional instruction. This design enabled direct comparison between the two groups, allowing the researcher to determine the extent to which PjBL contributes to spatial reasoning development through relevant statistical analysis.

Sample and Data Collection

A purposive sampling technique was applied to select students enrolled in a geometry course at Universitas Bosowa who were willing to participate in project-based instruction. The implementation of Project-Based Learning (PjBL) followed four main stages. First, the instructor introduced culturally relevant geometric problems drawn from local architectural designs and traditional patterns. Second, students were divided into small groups to design and plan their projects, which involved constructing geometric models that reflected both mathematical concepts and cultural contexts. Third, students carried out the projects collaboratively, engaging in activities such as measuring, sketching, and building two- and three-dimensional models. The instructor acted as a facilitator, providing guidance, resources, and formative feedback throughout the process. Finally, each group presented their project outcomes to the class, discussed the mathematical principles embedded in their work, and reflected on their learning experiences. This sequence ensured that students were actively engaged in problem-solving, collaboration, and contextual application of geometry while instructors scaffolded learning and evaluated progress. A total of 60 students were selected from a geometry course at Universitas Bosowa. All participants met the same academic performance criteria to reduce potential bias from extraneous variables. The students received instruction using the ethnomathematics-based Project-Based Learning (PjBL) model, which integrated culturally contextualized projects such as analyzing traditional architectural patterns, constructing geometric models, and presenting their findings. The instructor acted as a facilitator, providing scaffolding, feedback, and cultural resources throughout the process. The effectiveness of the intervention was evaluated by comparing students’ spatial ability before (pretest) and after (posttest) the implementation of the PjBL approach. This one-group pretest–posttest design allowed the researchers to assess the improvement in students’ spatial ability resulting from the intervention. Lessons primarily involved textbook explanations, static diagrams, and teacher-centered demonstrations without hands-on projects or cultural integration. While the control group focused on procedural problem-solving and written exercises, the experimental group emphasized collaboration, exploration, and contextual application. This distinction ensured a clear comparison between the innovative PjBL-ethnomathematics approach and traditional teaching methods.

Data were collected through three main instruments: a spatial ability test, classroom observation sheets, and student perception questionnaires. The spatial ability test was adapted from the Kit of Factor-Referenced Cognitive Tests (Babcock & Laguna, 1997) and the Purdue Spatial Visualization Test: Rotations (Maeda & Yoon, 2013), covering three domains: mental rotation, spatial visualization, and spatial perception. Content validity was confirmed by two experts in mathematics education, and a pilot test with 25 students produced a Cronbach’s alpha of 0.82, indicating high reliability. Classroom observations were conducted by two independent observers with expertise in mathematics education. Using structured observation sheets, they recorded levels of student engagement, collaboration, and interaction during the eight-week intervention; inter-rater reliability was 0.87. The student perception questionnaire consisted of 20 items adapted from the Motivated Strategies for Learning Questionnaire(Pintrichet al., 1991), focusing on motivation, conceptual understanding, and learning experiences. Expert validation confirmed its content relevance, and its reliability test showed a Cronbach’s alpha of .85, ensuring internal consistency.

Analyzing of Data

The collected data were analyzed using both descriptive and inferential statistical methods. Descriptive statistics (mean, standard deviation) were used to summarize pretest and posttest results. A paired-samples t-test was conducted to assess the significance of the differences between pretest and posttest scores within each group. Additionally, an Analysis of Covariance (ANCOVA) was employed to compare posttest scores between the two groups, while controlling for pretest scores, thereby ensuring a more accurate estimation of the treatment effect. Cohen’s d was calculated to measure the effect size of the intervention and determine the practical significance of the ethnomathematics-based PjBL approach in improving spatial ability.

Findings/Results

Normality Test

Table 1. One-Sample Kolmogorov-Smirnov Test for Normality

The results of the normality test using the Kolmogorov-Smirnov method show that both the pretest and posttest data are normally distributed. This is indicated by the Asymp. Sig. (2-tailed) values of .138 and .087 for the pretest and posttest, respectively, both of which exceed the significance threshold of .05. As the assumption of normality is met, further parametric analysis, such as the paired-sample t-test, is considered appropriate. This ensures the validity of statistical inference related to the effect of ethnomathematics-based PjBL on students' spatial abilities.

Descriptive Statistics and Paired Samples T-Test

Table 2. Paired Samples Statistics

Table 2 shows a substantial improvement in students’ spatial ability after the intervention. The mean pretest score was 66.51, while the mean posttest score increased to 84.57, reflecting a gain of 18.06 points. The relatively low standard errors indicate a tight distribution around the mean, strengthening the reliability of the sample means as estimators of population parameters. These findings provide initial evidence of the positive impact of ethnomathematics-basedPjBLon spatial ability.

Table 3. Paired Samples Correlations

As shown in Table 3, the correlation between pretest and posttest scores is positive but weak (r = .287). The p-value of 0.095 exceeds the significance threshold of .05, indicating that the correlation is not statistically significant. A correlation analysis was conducted between pretest and posttest scores to determine whether the level of improvement in spatial ability depended on students’ initial competence. The result showed a weak, non-significant relationship (r = .287, p> .5), indicating that the magnitude of improvement was not strongly influenced by students’ starting ability. This finding is important because it suggests that the instructional intervention benefited students across varying ability levels, regardless of whether they began with high or low spatial skills. In other words, the observed gains can be attributed more confidently to the ethnomathematics-basedPjBLmodel rather than to differences in students’ prior abilities.

Table 4. Paired Samples Test

The results of the paired-samples t-test in Table 4 reveal a statistically significant difference between the pretest and posttest scores (t(34) = -9.365,p< .001). The mean difference of -18.057 indicates a considerable increase in spatial ability following the intervention. The 95% confidence interval does not include zero, reinforcing the robustness of this finding. These results confirm that the application of ethnomathematics-based PjBL significantly enhances spatial reasoning skills among pre-service mathematics teachers.

Effect Size

Table 5. Paired Samples Effect Sizes

The effect size analysis using Cohen’s d in Table 5 indicates a large effect (d = -1.583), which is well beyond the conventional threshold of 0.8. The confidence interval ranges from -2.078 to -1.078, confirming the statistical and practical significance of the improvement. The negative value reflects that posttest scores are notably higher than pretest scores. This large effect supports the conclusion that the ethnomathematics-basedPjBLmodel has a strong and meaningful impact on enhancing students’ spatial abilities, particularly in the context of geometry education.

Discussion

The Effect of Project-Based Learning on Spatial Ability

The results of this study empirically confirm that Project-Based Learning (PjBL) has a substantial impact on improving the spatial ability of pre-service mathematics teachers. The paired samples t-test demonstrated a statistically significant increase in students' spatial test scores (t(34) = -9.365,p< .001), with the mean rising from 66.51 to 84.57 after the intervention. This result aligns withVygotsky (1978)sociocultural theory, which emphasizes that meaningful learning occurs through interaction with tools and socially situated tasks, such as those embedded inPjBL.During the teaching process, students worked in small groups to design and construct geometric models inspired by local cultural patterns, engaged in measuring and sketching tasks, and presented their projects to peers for discussion and feedback.Through engaging in project-based geometry tasks that relate directly to real-world spatial contexts, learners are given opportunities to construct mental models that are more robust and transferable. Such models are crucial in forming long-term cognitive structures associated with spatial reasoning, including mental rotation and spatial visualization, which are central components of geometry(Chen et al., 2023; Gilligan-Lee et al., 2022). These findings also resonate with the assertions ofZhu et al. (2023), who argue that authentic geometry tasks embedded in inquiry-based environments improve spatial cognition. Therefore, the improvement in posttest performance in this study reflects not only procedural success but also conceptual enrichment fostered by the learning model.

The cognitive mechanism underlying the effectiveness of PjBL can be explained by its three critical components: active exploration, collaborative construction, and reflective articulation. First, students actively manipulated geometric forms in real-world projects, which strengthened their ability to mentally rotate, transform, and visualize spatial relationships(Markopoulos et al., 2022). Second, group-based collaboration in PjBL allowed them to articulate and refine ideas through peer interaction, thereby deepening their conceptual grasp (Vygotsky,1978). Third, presenting and defending their geometric projects required students to translate between two- and three-dimensional representations, a process that directly enhanced mental visualization and spatial reasoning skills(Fujita et al., 2023). Collectively, these activities explain why students’ spatial ability improved significantly after the intervention. These stages collectively facilitated multimodal learning, integrating tactile, visual, and verbal modes of representation—an approach proven to enhance spatial understanding(Wilson, 2002). The structure of PjBL thus mirrors the cognitive progression necessary to effectively internalize geometric concepts.

The large effect size (Cohen’s d = -1.583) observed in this study substantiates the strength of the instructional intervention beyond statistical significance. According to Cohen (1988), an effect size above 0.8 is considered large, and in this case, the interval of [-2.078, -1.078] clearly excludes zero, confirming the robustness of the treatment effect. This suggests that the observed improvement in spatial ability is not due to chance but a direct result of the structured, meaningful engagement provided by the PjBL model. These findings are consistent with those reported by Murtiyasa and Budiningsih (2022), who found that students participating in project-based mathematics learning demonstrated superior spatial visualization skills compared to those taught via traditional methods. In contrast,Sariyasa (2017)found that conventional teaching can be sufficient for basic geometry; however, this study suggests that for developing higher-order spatial reasoning, more immersive approaches are required. Thus, while conventional instruction may suffice for foundational topics,PjBL fosters deeper cognitive engagement by encouraging students to analyze, synthesize, and apply geometric concepts in authentic contexts. This approach fosters critical thinking, problem-solving, and spatial reasoning—cognitive skills that are crucial for tackling complex geometry challenges in the 21st century.

Furthermore, a correlation analysis was conducted between pretest and posttest scores (r = 0.287,p = 0.095) to examine whether students’ learning gains were influenced by their initial abilities. The weak correlation indicates that improvement was largely independent of prior competence, suggesting that the intervention provided equitable benefits across different levels of spatial ability. This finding reinforces the inclusivity of the approach, as both high- and low-performing individuals were able to achieve meaningful progress. In the context of inclusive pedagogy, such findings are critical because they demonstrate that a well-designed instructional model can reduce disparities in cognitive outcomes(Baglieri, 2020). This aspect highlights the pedagogical value of PjBL not only as an effective strategy but also as a fair approach that supports diverse learners. The weak initial correlation further supports the conclusion that the learning model itself, rather than prior knowledge or ability, was the primary contributor to the observed gains. Therefore, the implementation of PjBL in teacher education programs should be viewed as a transformative practice that can elevate cognitive equity. Overall, the findings support a shift away from uniform instruction toward more active, differentiated learning approaches.

The Cultural Context: Role of Ethnomathematics in Enhancing Spatial Skills

The integration of ethnomathematics into PjBL played a catalytic role in this study by contextualizing mathematical concepts within culturally relevant frameworks. Ethnomathematics, as defined by D'ambrosio (1985), refers to the study of mathematical practices embedded in cultural traditions, which helps students make connections between formal mathematics and real-life experiences. In this study, local cultural elements, including traditional architecture and geometric motifs, were directly integrated into classroom activities. For example, students analyzed geometric patterns found in traditional houses and translated them into mathematical models, while motif designs were used as tasks to explore concepts of symmetry, transformation, and proportional reasoning. These culturally grounded tasks not only provided authentic learning contexts but also enhanced students’ cognitive and emotional engagement by connecting mathematics with their everyday cultural heritage. The incorporation of ethnomathematical elements allowed for situated learning, where students could anchor abstract spatial concepts in familiar and meaningful representations (Rosa & Orey, 2011). This approach is consistent with the tenets of constructivist learning theory, particularly in promoting knowledge construction through culturally relevant tasks. The contextual richness provided by ethnomathematical content enhanced student motivation, curiosity, and sense of ownership over the learning process. These benefits are particularly important in teacher education, where pre-service teachers must learn how to connect curriculum with students' lived experiences.

Several studies have emphasized the pedagogical advantages of integrating cultural content into mathematics instruction, especially in improving comprehension and reducing anxiety(Leonard, 2018). By incorporating ethnomathematics into geometry learning, students are exposed to tangible manifestations of abstract ideas, such as symmetry, rotation, and spatial proportion in traditional patterns. This approach not only bridges the gap between mathematics and culture but also transforms geometry into a subject that is both intellectually stimulating and personally relevant. In this study, students analyzed local geometric structures and replicated them in physical projects, thereby engaging in meaningful manipulation of space and form. As Piaget (1952) once suggested, learners construct knowledge through interaction with their environment, and in this case, cultural artifacts served as mediating tools. The familiarity of the content also helped reduce mathematics anxiety, particularly for students who struggle with spatial reasoning, making the classroom a more inclusive space. Therefore, the ethnomathematical approach contributed not only cognitively, but also affectively and socially, to students’ learning experiences.

Despite its many benefits, ethnomathematics remains underutilized in formal education, often perceived as secondary to core curriculum goals. However, this study demonstrates that its integration can yield tangible improvements in mathematical competencies, particularly spatial reasoning. The cultural component did not dilute the mathematical rigor; rather, it enhanced conceptual depth by providing multiple entry points for understanding geometry. Rosa and Orey (2011) emphasize that ethnomathematics does not replace formal mathematics, but rather complements it by enriching the learner’s interpretative framework. This complementary function was evident in students' ability to generalize geometric principles across cultural and mathematical domains. In doing so, the learners developed not only spatial skills but also mathematical fluency grounded in context. Therefore, ethnomathematics serves a dual function, cognitive and cultural, that reinforces both skill acquisition and identity affirmation in mathematics classrooms.

From a pedagogical standpoint, the use of cultural content aligns with the principles of culturally responsive teaching, which advocates for curriculum adaptations that reflect the diversity of learners. In teacher education, this approach is particularly relevant, as it equips future educators with strategies to bridge the cultural disconnects that often hinder learning in diverse classrooms(Mills, 2022). The success of the PjBL-ethnomathematics model in this study thus highlights its potential for replication across different cultural settings. WhileDesai et al. (2022)have cautioned against overgeneralizing the role of culture in mathematics, this study shows that when carefully designed, ethnomathematical integration can be both academically and culturally enriching. Consequently, the model promotes not only spatial competence but also pedagogical sensitivity, which is vital in preparing culturally responsive mathematics teachers. These findings suggest a need for a reevaluation of how cultural knowledge is addressed in mathematics teacher preparation programs.

Theoretical Implications: Cognitive and Embodied Perspectives

The findings of this study offer strong theoretical support for embodied cognition, a framework that posits knowledge acquisition as rooted in sensorimotor experiences and bodily interaction with the environment(Tanton, 2023). Within the context of geometry learning, PjBL-based ethnomathematical activities provided students with authentic interactions through hands-on tasks. For example, students constructed three-dimensional models of traditional cultural artifacts (e.g., houses, ornaments), measured and compared their geometric properties, and discussed how these shapes related to formal mathematical concepts. Such embodied activities reinforced spatial memory and cognition while connecting abstract geometry to tangible cultural contexts. These embodied interactions help learners engage not only with abstract spatial concepts but also with tactile, visual, and motor experiences that promote durable cognitive structures. The spatial tasks in this study, grounded in traditional design and architecture, fostered an integrated experience that aligns with Toussaint et al.  's (2020)assertion that physical manipulation enhances spatial reasoning. Moreover, such experiential learning is consistent with Vygotsky's (1978)notion of internalization, where socially mediated, physical tasks become mental operations over time. These theoretical links illustrate how ethnomathematics-based PjBL functions as more than instructional design-it becomes a cognitive environment that nurtures higher-order spatial thinking. Thus, the study extends embodied cognition beyond the laboratory, into culturally and pedagogically rich settings.

When students designed and built models of culturally inspired geometric structures, they practiced mental rotation, symmetry recognition, and spatial visualization-all in the service of physically creating real-world objects. These embodied practices are significant because they enable cognitive flexibility and the ability to operate across representations, which are critical for advanced mathematical thinking. AsMainali (2021)contends, engaging learners in rich representational practices bridges perceptual and conceptual knowledge in mathematics. Furthermore, when these tasks are framed within cultural contexts, they become more memorable and impactful due to emotional and cultural salience. This integration creates whatDuffels (2022)refers to as "grounded cognition," wherein conceptual processing is tied to specific perceptual and cultural experiences. Therefore, spatial learning does not occur in isolation, but is embedded in multisensory, socially meaningful activity systems.

Theoretically, this study aligns with contemporary perspectives suggesting that spatial ability is not solely the product of maturation (Piaget, 1952), but can also be enhanced through structured learning experiences. While our data do not directly resolve this theoretical debate, the observed improvements are consistent with research indicating that instruction plays a meaningful role in fostering spatial reasoning. The substantial improvement in students’ posttest scores, regardless of initial ability levels, suggests that spatial competence can be significantly enhanced through pedagogical design. This aligns with more recent sociocultural and constructivist views that prioritize environment, tools, and interaction in the development of cognitive skills(Webb & Whitlow, 2019). In this light, the instructional context becomes a key determinant of how spatial reasoning is nurtured, especially when infused with meaningful cultural and collaborative elements. By designing tasks that engage multiple cognitive modalities and social dynamics, educators can accelerate spatial development beyond what is assumed to be naturally attainable. Therefore, this study provides empirical weight to theoretical models that argue for the modifiability of spatial cognition through purposeful intervention.

In conclusion, the success of the intervention adds depth to the theoretical discourse around the integration of body, culture, and cognition in mathematical learning. Embodied cognition, when operationalized through ethnomathematical and project-based tasks, provides a comprehensive framework for understanding how students internalize spatial knowledge. This has implications not only for how geometry is taught, but for how we conceptualize the acquisition of abstract mathematical thinking. The cultural grounding of the tasks adds a layer of situated cognition, ensuring that learning is not only effective but contextually meaningful(Gasparini et al., 2018). This hybrid of embodied, sociocultural, and constructivist theories provides a richer lens through which to interpret the success of instructional interventions. Ultimately, the results demonstrate that when learning environments reflect the cultural and sensory dimensions of students’ lives, the outcomes are both cognitively and theoretically robust.

Practical Implications and Recommendations for Future Research

The practical implications of this study are significant for the preparation of mathematics teachers, particularly in designing instructional strategies that are both effective and culturally responsive. Integrating PjBL with ethnomathematics creates a powerful pedagogical synergy that aligns with the competencies required in contemporary classrooms, especially under frameworks like Indonesia’s Merdeka Belajar curriculum. This integration supports not only the development of hard skills such as spatial ability, but also soft skills, including collaboration, creativity, and cultural awareness skills,increasingly demanded in 21st-century education(Sugiyantoet al., 2023). Through meaningful tasks rooted in local traditions, future teachers are exposed to an instructional model that is both academically rigorous and socially relevant. This exposure helps them envision their future teaching not merely as content delivery, but as a process of connecting mathematics to students’ real-life contexts. Such alignment with culturally sustaining pedagogy fosters deeper engagement and higher retention of mathematical concepts among learners.

In operational terms, the implementation of ethnomathematics-basedPjBLdoes not require sophisticated technological infrastructure, making it accessible for institutions with limited resources. While augmented reality and other advanced tools can enhance spatial instruction(Darwish et al., 2023). This study demonstrates that culturally grounded projects alone are sufficient to achieve significant gains. This finding is especially important in rural or under-resourced areas, where access to technology may be limited but cultural richness abounds. By leveraging local wisdom and artifacts, educators can offer immersive learning experiences with minimal financial investment. Moreover, the approach promotes sustainability by encouraging the use of locally available materials and community knowledge in project design. Thus, the model is not only pedagogically sound but also adaptable and scalable in diverse educational contexts.

However, the study also acknowledges limitations that future research should address to strengthen the validity and applicability of the findings. One such limitation is the inability to isolate the effect of ethnomathematics fromPjBL, given the hybrid nature of the intervention. As Habib and Pius (2022) noted, disentangling the impact of culture from instructional strategy is methodologically challenging but crucial for fine-tuning pedagogical recommendations. Future studies could employ factorial experimental designs to examine the individual and combined effects of each component. Another limitation involves the duration of the intervention; while eight weeks yielded significant results, longitudinal studies could explore whether these gains are retained over time. Additional research may also investigate how individual differences, such as learning styles or prior cultural exposure, influence the effectiveness of this instructional approach.

Given these considerations, future research should expand the scope of ethnomathematics-basedPjBLto encompass a broader range of disciplines, educational levels, and cultural contexts. Studies could investigate its applicability in early childhood settings, vocational training, or even teacher professional development programs. Additionally, integrating digital tools with ethnomathematical content, such as using Desmos or GeoGebra for modeling traditional patterns, may further enhance spatial reasoning and engagement(Suryawan &Sariyasa, 2018). Exploring how pre-service teachers apply these instructional models in their own future classrooms would also provide valuable insights into their long-term pedagogical impact. As Dvoryatkina (2022)suggests, the combination of cultural, technological, and inquiry-based learning may represent the future of mathematics education. Ultimately, this study lays a foundation for innovative, inclusive, and context-rich teaching practices that not only enhance mathematical thinking but also affirm students' cultural identities.

Conclusion

This study has provided compelling empirical evidence that integrating Project-Based Learning (PBL) with ethnomathematics significantly enhances the spatial ability of pre-service mathematics teachers. The use of a quasi-experimental design with pretest-posttest comparisons revealed a statistically significant improvement in spatial reasoning skills, as demonstrated by the large effect size (Cohen’s d = -1.583) and a substantial increase in mean test scores following the intervention. These findings underscore the importance of instructional models that engage learners through authentic, collaborative, and culturally relevant tasks.PjBL facilitates active exploration and conceptual construction, while ethnomathematics contextualizes abstract mathematical concepts within meaningful cultural narratives, together creating a cognitively rich learning environment.

The theoretical contributions of this study are grounded in constructivist and embodied cognition perspectives, which affirm that knowledge acquisition is best supported by interaction with physical, social, and cultural contexts. By involving students in the design and construction of geometric representations rooted in traditional forms, the intervention stimulated not only spatial thinking but also affective engagement and cultural awareness. These findings challenge developmentalist assumptions that spatial ability is fixed or maturational, demonstrating instead that it can be significantly developed through instructional design. Moreover, the integration of ethnomathematics validates the cultural assets students bring into the classroom, reinforcing mathematics as a humanistic and socially embedded discipline.

Practically, the success of this instructional model offers a viable and accessible approach to improving geometry education within teacher training programs. It provides a template for culturally responsive pedagogy that is both effective in promoting cognitive growth and inclusive in honoring diverse backgrounds. This model aligns well with national curricular reforms such as Indonesia’s MerdekaBelajar, which emphasize context-based and student-centered learning. Importantly, the approach can be implemented with minimal technological requirements, making it scalable across a variety of educational settings, especially in resource-limited contexts where cultural capital is abundant.

Future research should explore the sustainability and transferability of this approach across disciplines and educational levels. It is recommended that further studies disentangle the distinct effects ofPjBLand ethnomathematics through factorial designs and investigate how digital tools can be integrated to expand the model’s impact. Additionally, longitudinal research is needed to assess long-term retention and application of spatial reasoning skills beyond the classroom. Ultimately, this study contributes to a growing body of evidence that mathematics education can—and should—be transformative, inclusive, and deeply connected to the cultural realities of learners.

Recommendations

The findings of this study offer several important directions for future research and practical implementation in mathematics education. First, researchers are encouraged to further investigate the independent and combined effects of Project-Based Learning and ethnomathematics through factorial experimental designs. Such studies could help disentangle the specific contributions of each instructional element and clarify the mechanisms by which they enhance spatial reasoning. Additionally, longitudinal studies should be conducted to assess the sustainability of spatial ability gains over extended periods and to explore how these skills transfer into classroom teaching practices among future educators.

Second, researchers may consider expanding the cultural scope of ethnomathematical integration by exploring geometric forms and patterns from diverse ethnic groups, indigenous knowledge systems, or local architecture. This would not only strengthen the theoretical understanding of culturally responsive pedagogy but also enhance the generalizability and adaptability of the instructional model across regions and educational contexts. Incorporating digital technologies such as GeoGebra, Desmos, or augmented reality into ethnomathematics-basedPjBLmay also offer new possibilities for supporting dynamic visualization and interaction, especially in online or hybrid learning environments.

For practitioners, particularly mathematics educators and teacher trainers, this study underscores the value of designing instructional activities that are both project-oriented and culturally embedded. Curriculum developers are encouraged to include local cultural artifacts and traditional mathematical practices as learning resources within geometry units. Teacher education programs should also emphasize training in culturally responsive teaching methods, equipping pre-service teachers with the pedagogical skills necessary to connect abstract mathematical content with students’ sociocultural experiences. This approach not only enhances engagement and comprehension but also fosters a deeper appreciation of mathematics as a humanistic discipline.

Finally, institutional leaders and policymakers should support the development and implementation of learning models that integrate cultural relevance with cognitive skill development. Investment in community-based educational resources, interdisciplinary collaboration, and professional development focused onPjBLand ethnomathematics can further institutionalize this innovative approach. In doing so, education systems will be better equipped to cultivate mathematically competent, culturally aware, and pedagogically versatile teachers who are prepared to meet the demands of modern, diverse classrooms.

Limitations

Although this study provides valuable insights into the effectiveness of ethnomathematics-based Project-Based Learning (PjBL) in enhancing the spatial ability of pre-service mathematics teachers, several limitations should be acknowledged. First, the study was conducted within a single university setting with a relatively small sample size (N = 60), which may limit the generalizability of the findings. Future studies involving multiple institutions and larger, more diverse samples are recommended to enhance external validity and explore variations across educational and cultural contexts.

Second, the research design combined both PjBL and ethnomathematics into a single intervention, which limits the ability to isolate the specific effects of each component. Although the integrated model yielded significant outcomes, it remains unclear whether the observed improvements were primarily driven by the project-based structure, the cultural content, or the interaction between the two. Future experimental designs using factorial or component analysis approaches are needed to disentangle these effects and refine the instructional model further.

Third, the duration of the intervention was limited to eight weeks, which may not be sufficient to fully capture the long-term development and retention of spatial abilities. While the post-intervention results showed significant improvement, it is unclear whether these gains would persist over time without continued reinforcement. Longitudinal studies are necessary to investigate the stability and transferability of the acquired spatial skills into real-world teaching practices.

Lastly, the study focused primarily on cognitive outcomes, particularly spatial ability, while potentially overlooking affective and behavioral dimensions of learning, such as student motivation, cultural identity development, and pedagogical transformation. Qualitative data and a mixed-method approach in future research may provide deeper insights into how students experience and respond to culturally contextualized, project-based learning environments. Recognizing these limitations not only clarifies the scope of the current study but also opens pathways for continued innovation in mathematics education research.

Authorship Contribution Statement

Jainuddin: Conceptualization, design, analysis, writing. Tatang Herman: Editing/reviewing, supervision.