The instruction for medical students majoring in clinical medicine was structured into two phases. The study population consisted from the 2021 and 2022 cohorts (age range 19-21 years; 55% female, 45% male), all of whom had completed fundamental courses in anatomy, cell biology, physiology, statistics, immunology, and pathology prior to participation. The first phase involves classroom lectures in the second semester of the freshman year, while the second phase utilizes PBL methodology for discussion-based teaching in the first semester of the sophomore year (4 h/2 sessions). During the first PBL session, the primary tasks are for teachers to present relevant case studies and for students to engage in group discussions. The case studies center around three scenarios: antenatal checkups for pregnant women, auxiliary examinations, and childbirth. Through each scenario, accompanied by learning objectives and questions, students engaged in group discussions to jointly explore issues such as the causes of fetal malformation, diagnostic methods, and potential management of doctor-patient relationships. During this process, the teacher actively guided the discussions, providing necessary support and feedback, ultimately setting the themes for the groups’ presentations in the second session.

After the first session, each group’s chairperson led the secretaries and reporters in preparing their presentation content based on the assigned themes and internal roles. This involved researching materials, resolving questions, determining the presentation format, and conducting peer evaluations within the group. Meanwhile, the teacher provided assistance through online platforms like Superstar or QQ, answering questions and ensuring students completed their preparation on time (15–17). During the second session, each group presented their work, either through role-playing scenarios, video presentations, PowerPoint demonstrations, or proposals for practical activities promoting eugenics and prenatal care. Following the presentations, students conducted peer evaluations among groups. Finally, the teacher provided comments and a summary. After class, students completed a questionnaire related to the PBL teaching methodology designed by the teacher, and the teacher analyzed the questionnaire results statistically to understand students’ learning progress. The Figure 1 illustrates the second session flowchart of the PBL teaching process.

Employing a diversified evaluation approach that encompasses pre-class peer evaluation within groups, in-class peer evaluation between groups, and post-class questionnaires, allows students to fully participate in the evaluation process (18–20). To ensure objectivity, all peer evaluations were conducted using a blinded review system (anonymous assessment), and faculty members independently scored each group using the same standardized criteria. The scores from pre-class and in-class peer evaluations are included in the students’ overall course grades.

This scoring mechanism is designed with clear and precise evaluation criteria to ensure objectivity and feasibility. The assessment is divided into two main components: pre-class peer evaluation within groups and in-class peer evaluation between groups, each with specific scoring guidelines. The detailed criteria and point ranges are outlined in the table below (Table 1).

In summary, this diversified evaluation approach not only ensures fairness and objectivity in assessing student performance but also fosters an environment conducive to active learning, teamwork, and continuous improvement.

This study employed multiple assessment methods to collect data, including intra-group peer evaluation, inter-group peer evaluation, and questionnaires survey. Intra-group peer evaluation focused on the performance of team members during collaborative learning activities, while inter-group peer evaluation assessed the collaboration and competition dynamics between different groups. Questionnaires survey were used to gather students’ feedback on teaching methods, learning outcomes, and course satisfaction. To ensure the comprehensiveness and representativeness of the data, all assessment methods were implemented across multiple classes and conducted repeatedly to capture diverse teaching scenarios and student perspectives.

Differences in the inter-group peer evaluation score were analyzed using Student’s t-test in GraphPad Prism7; results are expressed as mean ± standard deviation (SD), with a significance level established at p < 0.05. Both Cronbach’s alpha (for reliability) and chi-square tests (for comparative analysis) were conducted using SPSS.

The results of intra-group peer evaluation showed no significant differences, indicating that group members recognized each other’s earnest and active participation. This component serves as a mutual supervision mechanism during the preparation phase. It evaluates individual contributions based on task completion, work quality, collaboration, and timeliness. This approach prevents free-riding, ensures accountability, and fosters a collaborative and productive team environment.

The pre-class peer evaluation provides teachers with valuable insights into each student’s level of engagement and contribution within their group. By analyzing the evaluation data, teachers can identify students who may need additional support or motivation, as well as recognize those who excel in leadership and collaboration. This feedback can inform targeted interventions, such as personalized guidance or adjusted group dynamics, to enhance the overall learning experience.

During the second-class session, each group assigned scores to other groups based on their preparation, presentation format, and overall effectiveness. The evaluation revealed significant differences in scores between the top-performing and the lowest-performing groups (Figure 2), demonstrating a considerable variation in performance among different groups. Notably, faculty assessments demonstrated consistent scoring trends with student evaluations, validating the reliability of the peer-review process. This disparity can be attributed to several key factors: ① case selection: the choice of cases played a critical role in the performance differences. Top-performing groups often selected cases that were highly relevant, engaging, and aligned with the learning objectives, which allowed them to demonstrate a deeper understanding and application of the concepts. In contrast, some lower-performing groups chose cases that were either too complex or not sufficiently challenging, which limited their ability to showcase their skills effectively. ② Group member abilities: the composition and abilities of group members also significantly influenced the outcomes. Groups with members who possessed strong research, organizational, and presentation skills tended to perform better. For example, some groups excelled in live scenario simulations due to members’ strong communication and improvisation skills, while others struggled with video recordings due to limited technical expertise. ③ Preparation levels: the varying levels of preparation among groups further contributed to the performance differences. Top-performing groups invested more time in researching their cases, rehearsing their presentations, and refining their delivery, which resulted in a more polished and impactful performance. On the other hand, some lower-performing groups lacked thorough preparation, leading to less coherent and less engaging presentations. ④Presentation formats: the diverse presentation formats adopted by each group, including live scenario simulations, video recordings and playback, poster design and promotion planning, and charity event planning, also played a role in the observed differences. While some formats, such as live simulations, allowed for dynamic interaction and immediate feedback, others, like video recordings, required more technical proficiency and planning, which not all groups were able to achieve equally.

During the presentation showcase, every student act as a judge, evaluating other groups based on content quality, presentation format, delivery, and overall effectiveness. Students are also required to provide written comments, which encourages active listening, critical thinking, and a deeper understanding of both their own group’s work and that of others.

The inter-group peer evaluation offers teachers a comprehensive view of how students perceive and critique their peers’ work. By reviewing the written comments and scores, teachers can identify common strengths and weaknesses in students’ presentations, such as recurring issues with content organization or delivery. This information can be used to refine teaching strategies and guide students in adopting more effective methods for learning, researching, and summarizing.

In addition to the insights gained from peer evaluations, the study could be further enriched by incorporating teacher-curated case lists. By providing a selection of cases that are equally challenging for all students, teachers can ensure that every student engages with material that is appropriately rigorous. This approach not only levels the playing field but also encourages a more uniform development of critical thinking and analytical skills across the classroom. By curating these cases, teachers can facilitate deeper discussions and more meaningful evaluations, thereby enhancing the overall learning experience for students.

The third evaluation method employed in this study was a post-class questionnaire survey to collect data. The participants were students from the class of 2021 and 2022 in the clinical medicine program. A total of 331 valid questionnaires were collected and included in the analysis. Before conducting the questionnaire analysis, we performed a Cronbach’s reliability analysis, which yielded a Cronbach’s α coefficient of 0.768, indicating that the reliability quality of the research data is good, thus justifying the subsequent analysis (21). Table 2 provides a comprehensive summary of the questionnaire questions and their detailed analysis, highlighting the impact of the PBL teaching method on students’ understanding of congenital malformations. The table is organized as follows:

These findings underscore the remarkable efficacy of PBL in teaching congenital malformations, a topic characterized by a vast array of types and symptoms. Traditional teaching methods exhibit limitations, as instructors often cover limited content, leaving students in a passive reception role with difficulties in internalizing the knowledge. PBL’s strength lies in its ability to engage students actively through guided case studies, resembling popular narrative-driven puzzle games such as “Murder Mystery Parties” and “Escape Rooms” among young adults, thereby fostering interest and motivation (22–24). Moreover, PBL’s group-based approach fosters teamwork and communication skills as students collaborate to solve problems. By applying their knowledge and skills to real-world scenarios, PBL nurtures students’ divergent thinking and innovative abilities throughout the problem-solving process (Figures 3–6).

While this study provides valuable preliminary evidence regarding the effectiveness of PBL in congenital malformations education, several important limitations must be acknowledged along with their corresponding future research directions:

First, the absence of a control group taught through traditional lecture-based methods limits our ability to definitively attribute the observed outcomes solely to PBL pedagogy (30). Future studies should incorporate a randomized controlled design with parallel cohorts receiving conventional instruction to enable direct comparison of relative effectiveness, particularly in measuring knowledge acquisition rates and long-term retention. Such comparative data would substantially strengthen the evidence base for curricular decision-making.

Second, the relatively short duration of the PBL intervention (4 h over 2 sessions) may not have fully captured the potential benefits of this instructional approach. While we observed significant improvements in student engagement and self-reported knowledge, extending PBL implementation across an entire semester with progressively complex cases would allow for more robust development of clinical reasoning skills and better assessment of knowledge retention over time. This extended timeframe would also facilitate the incorporation of spaced repetition techniques known to enhance long-term memory consolidation (31).

Third, our reliance on subjective self-assessment measures, while providing useful qualitative insights, represents a methodological limitation in objectively quantifying knowledge gains. Moving forward, the development and validation of standardized pre- and post-tests specifically targeting congenital malformations knowledge would provide more rigorous quantitative assessment of learning outcomes. These instruments should include both factual recall items and clinical application scenarios to comprehensively evaluate different cognitive domains. Additionally, incorporating objective structured clinical examinations would allow assessment of practical skill development (32, 33).

Moreover, there is limited consideration of confounding factors such as students’ prior knowledge, learning styles, and instructor influence (34–36). It is crucial to investigate whether the observed improvements in student performance could be attributed to the effectiveness of the instructors rather than the PBL approach itself. Addressing these variables in future research will provide a clearer understanding of the factors contributing to student success.

Finally, the study does not discuss whether knowledge retention is sustained beyond the short-term evaluation (31). A follow-up discussion on the long-term application of knowledge in clinical settings would enhance the study (37). Investigating how well students retain and apply their knowledge over time will provide valuable insights into the lasting impact of PBL on their clinical competencies.

The single-institution nature of this study may also limit the generalizability of our findings to other educational contexts with different student demographics or curricular structures. To enhance external validity, future research should employ a multi-center design involving medical schools from diverse geographical regions with varying educational resources (38). This expansion would not only improve the robustness of the findings but also provide valuable insights into how institutional factors may influence PBL implementation outcomes. Such comparative institutional data could inform tailored adaptations of PBL approaches to different educational settings.

The proposed methodological improvements, including controlled comparisons, extended intervention duration, objective assessment tools, and multi-institutional collaboration, will collectively address current study limitations while significantly advancing our understanding of optimal PBL implementation strategies in medical education. By incorporating these enhancements into future research designs, we can generate more robust evidence to inform curricular reforms in both embryology and congenital malformations education.