Introduction

Over the past three decades, the widespread integration of information technology in education has fundamentally reshaped learners’ needs and expectations. In response to these shifts, the flipped classroom (FC)model has emerged as a prominent model and is even considered the future of education (H.-L.Tsai & Wu, 2020). FC is essentially a reorganization of classroom and out-of-class time, shifting learning decisions from teachers to students (McLaughlin et al., 2014). It facilitates the provision of long-term learning opportunities that are tailored to learners’ competencies, contextual conditions, and individual characteristics (Akçayır&Akçayır, 2018), with such personalization being supported through digital platforms (Al-Shabibi & Al-Ayasra, 2019; Huda et al., 2021; Jdaitawi, 2019; Zainuddin, Zhang et al., 2019). This pedagogical model is recognized as one of the most effective approaches for integrating technology into education while preserving the pedagogical value of direct teacher-student interaction (Zohi, 2014). Consequently, the FC strategy has garnered significant attention in developed countries (Al-Shabibi & Al-Ayasra, 2019) and has emerged as a prominent research trend within the field of educational science (Kozikoglu, 2019;Long et al.,2017). Empirical evidence from multiple studies indicates that FC yields positive educational outcomes, including enhanced learner engagement (Subramaniam & Muniandy, 2019), increased learning motivation (Abeysekera & Dawson, 2015; Awidi & Paynter, 2019), development of critical thinking skills (DeRuisseau, 2016), advancement of problem-solving competencies (Hwang & Chen, 2019; Ivan et al., 2023), and the promotion of self-directed and active learning (El-Senousy&Alquda, 2017).

The rapid increase in studies on the FC model has highlighted the need for bibliometric analysis to provide an overall picture of this field (Bozdağ et al., 2021). Although there are many bibliometric studies on FC models at different levels and fields, most of the studies in the past decades have focused on: First, bibliometrics on FC in general scope (Al-Shabibi & Al-Ayasra, 2019;Çakır et al., 2021; del Arco et al., 2022;Yang et al., 2017;Yulita, 2024; F. Zhang et al., 2024); Second, bibliometric analyzes of FC in specific academic disciplines such as in mathematics education (Kadarismaet al., 2024; Loet al., 2017; Özdemir, 2024; Soebagyo & Saamah, 2023; Sulistyowati et al., 2024), biology education (Bozdağ et al., 2021; Maltoet al., 2018), science education (Yokhebedet al., 2023), technology education (Barreto et al., 2018; Karabulut-Ilguet al., 2018), reading comprehension (AlcayhuamánGilet al., 2022), ESL education (Yusoffet al., 2024), introductory programming courses (Sobral, 2021), and medical education (P.Zhang et al., 2023); Third, bibliometrics of FC in the higher education context such as Lundin et al. (2018), Gong (2023), Rakhmalinda(2024). However, there is currently a lack of systematic and specific statistical analysis for the K-12 educational context.

Therefore, the purpose of this study is to address the aforementioned gap by conducting a comprehensive analysis of the scientific landscape on FC in K-12 education from 2014 to 2024. The unique contribution of this research lies in its specialized focus on K-12 education, which has received little research attention, and in establishing a scientific mapping to investigate thematic research trends, patterns of international collaboration, influential authors, and institutions over a decade-long timeline.

This study aims to answer the following research questions:

*Research question 1: What are the publication trends in FC research within K-12 education from 2014 to 2024?

*Research question 2: What prominent themes and emerging research directions can be identified through keyword analysis?

*Research question 3: Which international collaborations and institutions have played leading roles in advancing FC research in K-12 education?

LiteratureReview

Flipped Classroom

FC is a modern instructional model in which the traditional roles of teachers and students are restructured. In particular, theoretical lectures are delivered to students for self-study at home through materials such as video lectures, readings, or online learning tools. Classroom time is then primarily devoted to active learning activities such as discussions, problem-solving, group work, and direct practice (Bergmann & Sams, 2012; Bishop & Verleger, 2013; Li et al., 2022). The FC strategy involves two types of learning activities: individual study outside of class, which includes watching videos and using instructional materials provided by the teacher, and face-to-face learning in class, where direct interaction with both the teacher and peers is emphasized to engage in higher-order learning tasks. At its simplest, the FC model is defined as “lesson at home, homework at school” reversing in-class instruction and out-of-class activities (Abeysekera & Dawson, 2015; Awidi& Paynter, 2019; Behmanesh et al., 2022). This model is learner-centered and grounded in constructivist learning theories, emphasizing the importance of learners creating social meaning from pre-learned materials and newly acquired knowledge (Olakanmi, 2017; Polat &Karabatak, 2022).

According to Bloom’s taxonomy, lower-order cognitive processes, such as remembering and understanding, are achieved during out-of-class preparation, while higher-order skills, including application, analysis, evaluation, and creation,are developed during in-class activities through direct interaction and support from teachers and peers (J.W.Baker, 2000). The collaborative classroom environment thus becomes a dynamic learning space that enhances interaction for both teachers and students (Abeysekera & Dawson, 2015; Bergmann & Sams, 2012). In this setting, face-to-face sessions increasingly focus on problem-solving activities conducted in groups under the guidance of teachers and in collaboration with classmates, aiming to foster higher-order thinking skills (Abeysekera & Dawson, 2015; Bates et al., 2017; Kong, 2014; Swearingen, 2016; Zainuddin, Haruna, et al., 2019).

In modern classrooms, the FC model also transforms the teacher's role. Teachers become facilitators, supporters, motivators, and monitors of students’ progress across tasks and projects. With students’ prior preparation, teachers gain more time for meaningful interactions, deeper engagement in effective instructional activities (Al-Hasanat, 2022; Bergmann & Sams, 2012), and more opportunities to provide feedback (Subramaniam & Muniandy, 2019). This approach addresses the limitations of traditional classroom time, enhances interaction, and encourages active student participation (Barak &Shakhman, 2008; Schultz et al., 2014), while freeing up time for activities such as case studies, discussions, assessments, exercises, and simulations (Srinivasan et al., 2018). In this model, learners play a significant role, actively engaging with technology in their out-of-class study, cultivating critical thinking, self-directed learning, experiential learning, social communication, and collaboration to acquire 21st-century skills. FC strategies are particularly effective in personalizing students’ learning experiences and increasing their motivation (Awidi& Paynter, 2019;Turan & Göktaş, 2018). The provision of online learning materials throughout the semester offers students flexible opportunities to gain experience, even in cases where they may miss a class for any reason. Moreover, this strategy supports ongoing learning beyond scheduled class time through after-school practice activities, helping learners achieve mastery (Çakıret al., 2019;Fulton, 2012; Rutkowski &Moscinska, 2013). FC also enhances students’ self-awareness, confidence, and communication skills (Al-Shabibi & Al-Ayasra, 2019; Namaziandost& Çakmak, 2020; Olakanmi, 2017), bridging the gap between theoretical knowledge and real-world application (Al-Shabibi & Al-Ayasra, 2019; Tomory & Watson, 2015), and potentially improving academic performance (Dixon & Wendt, 2021; Imania& Bariah, 2020), so most learners feel satisfied when studying with this model (Shen & Khechornphak, 2024).

Bibliometric Research on FC

The number of publications on FC has increased rapidly in recent years, resulting in the emergence of a research direction that focuses on the bibliometric analysis of FC. These studies used various database sources such as Web of Science, Scopus, and Google Scholar, and tools such as VOSviewer, Excel, HistCite, CiteSpace, R (Bibliometrix),and Publish or Perish.

Using the Web of Science data source, Yang et al. (2017) conducted a quantitative analysis with Excel and HistCite to examine the global growth and development of FC research productivity, focusing on the number of articles, countries, and authors as reflected in SCI/SSCI publications from 2000 to 2015. Based on the VOSviewer tool, H.-L. Tsai and Wu(2020) analyzed the bibliometric characteristics of FC publications in the SSCI and SCIE from 2000 to 2019. Using the same dataset on FC from the Web of Science, while the study byÇakıret al. (2021) emphasized keyword mapping, citation network mapping, and analyses of authors and collaborating countries for the period 2015-2019 through theVOSviewertool, the study bydelArco et al. (2022) extended the analysis to examine major trends and emerging strategic directions during the period from 2007 to 2021.P.Zhang et al. (2023) conducted a bibliometric study ofthe FC model in medical education based on a combination of diverse tools (VOSviewer, R, and Excel) and exploited from Web of Science data sources within a decade (2012-2022).

Approaching bibliometric research on FC from the Scopus data source has also become a research trend. Through Microsoft Excel and VOSviewer tools,Yulita's (2024) study emphasized the analysis of Keywords, bibliographical data, and citation information about FC in the period 2012-2023. Focusing on the years 2019 to 2023 and based on the VOSviewer tool, Chitambram and Sazalli (2024) conducted a bibliometric analysis, which includes citation, authorship, and keyword analysis.

In addition to general bibliometric research, studies specifically exploring FC in higher education have also emerged, including those by Lundin et al. (2018), Limaymanta et al. (2021), Gong (2023), and Rakhmalinda (2024), owing to the relative ease of implementing the FC model at the tertiary education level. In which, the study of Lundin et al. (2018) used a structured overview method, classifying 31 highly cited documents according to theory and research design, Limaymanta et al. (2021) combined data from bothWoSand Scopus with 4 analysis software (EndNote X9, Publish or Perish 7, Excel 2019 andVOSviewer), and Gong (2023) was conducted through the use of the CiteSpace tool, and the study of Rakhmalinda (2024) exploited data on FC from Scopus source for the period 2012-2022 and the tool based on Excel 2019 andVOSviewer. In addition, with the application of Lotka's Law, the study of Kushairi and Ahmi (2021) showed the potential for predicting scholarly productivity as a new direction in bibliometric research on FC. At the K-12 level, bibliometric studies tend to clarify FC patterns by subject, database, and countries with representatives such as Bozdağ et al. (2021) in the field of biology, Soebagyo and Saamah (2023) in the field of mathematics. However, despite the previous research results, bibliometric studies on the FC model in K-12 education still remain a gap that needs to be filled in the context of increasingly developing technology and the continuous improvement of high school students' ability to use technology in learning.

Methodology

Data Search

The data search was conducted as follows:

Step 1- Identifying the research topic and search string:We utilized data from the Scopus database due to its comprehensive search capabilities across various fields within the social sciences and natural sciences. The Scopus database was chosen for this study due to its position as one of the most extensive and reputable indexing platforms in scientific research today. Scopus is recognized as the world's largest abstract and citation database (Burnham, 2006; Falagas et al., 2008), with over 82 million records and 1.7 billion cited references, covering 240 different fields of expertise (Magadán-Díaz & Rivas-García, 2022). Scopus' broad scope and multidisciplinary nature ensure the presence of high-quality peer-reviewed literature, making it a preferred data source in bibliometric analysis studies globally (Ahmi et al., 2019).

To ensure that studies on the topic of FC were thoroughly searched without omissions, we employed keywords such as “flipped classroom” or “flipped classrooms,” while restricting the search to secondary education levels using the keywords “K-12,” “primary school,” “secondary school,” and “high school”. These keywords were searched within the title, abstract, and keywords of the documents. The specific search string was as follows: (TITLE-ABS-KEY(("flipped classroom" OR "flipped classrooms") AND ("K-12" OR "primary school" OR "secondary school" OR "high school"))), journal articles, in English, conducted on December 27, 2024.

Step 2-Data search and filtering: Based on the search string identified in Step 1, we limited the search timeframe to the past 10 years, from 2014 to December 2024. The search yielded a total of 358 relevant documents related to the research topic. These 358 documents consisted of scientific articles published in specialized journals, with the language of publication restricted to English. However, to ensure that the collected documents were aligned with the overarching theme of FC in K-12 education, the authors conducted a filtering process by directly reading the titles, abstracts, and research summaries of the 358 documents. The data screening process in this study was performed manually by four members of the research team. Each member participated in reading and independently evaluating all 358 articles collected from the Scopus database, based on criteria related to the FC model in the K-12 educational context. After the individual evaluations, the team conducted group discussions to compare the results and address any disagreements. Controversial articles were discussed in detail until a consensus was reached.

As a result, only 262 documents were included in the bibliometric analysis using the VOSViewer software. The 96 documents excluded were removed because their titles or abstract content were not directly related to secondary education levels or were distant from the topic of FC.

Step 3 - Included:Finally, the dataset included a total of 262 publications for analysis.

Figure 1. PRISMA Process for Data Search, Screening, and Cleaning

Data Analysis

To visualize and analyze the data, we utilized Microsoft Excel andVOSviewer(van Eck & Waltman, 2019).VOSvieweris a bibliometric mapping technique designed to replace the Multidimensional Scaling (MDS) technique (van Ecket al., 2010).VOSviewerenables the creation of maps and visualization of data networks and the analysis of factors,including journals, authors, individual studies, and can be constructed based on citations, bibliographic coupling, co-citations, or co-authorship relationships (van Eck & Waltman, 2017). Furthermore,VOSvieweralso performs text mining functions to analyze the content of scientific documents, particularly the titles and abstracts of studies. This approach allows researchers to identify research trends over an extended period, while also forecasting and making recommendations on potential and feasible research topics for the future (Hallinger & Nguyen, 2020; Pham-Ducet al., 2021). Descriptive data, including the distribution of journals, authors, and the most productive countries, were analyzed using Excel.

Findings

Research Question 1: What Are the Publication Trends in FC Research Within K-12 Education from 2014 to 2024?

Growth in Publications

Figure 2. Increase in the number of publications on FC in K-12 education (2014- 2024)

The statistical chart of publications over the ten-year period from 2014 to 2024 reveals that research on FC was still limited between 2014 and 2016, with the lowest number of publications recorded in 2014 (4 articles). A notable surge occurred between 2020 (41 articles) which coincided with the global outbreak of the COVID-19 pandemic. The highest number of publications was observed in 2023, reaching a peak of 44 articles. This chart has been redrawn based on filtered data collected up to December 27, 2024, and the analysis has been revised accordingly to reflect the actual figures.

Key Countries

Figure 3. Map of Citation-Countries for the Period 2014-2024

(57 countries meet the threshold, minimum number of documents per country: 1)

Total Link Strength (TLS) is an important index used in scientific network analysis, especially in software such as VOSviewer, reflecting the connection and scholarly influence between entities such as authors, organizations, countries, keywords, journals, etc., with other objects in the same network (van Eck & Waltman, 2017, 2019).

Analysis of the citation map in Figure 3 and Table 1 shows that the United States, Taiwan, and Hong Kong occupy central roles in the FC research network, as evidenced by their high citation counts (over 1,100 citations, with Hong Kong exceeding 1,300) and outstanding TLS scores of 108, 109, and 104, respectively. In addition, Australia and China stand out as key regional collaboration hubs. Although countries such as Vietnam, Ghana, and Brunei still demonstrate modest TLS, their presence within the international research collaboration network indicates potential for expanding research efforts and strengthening academic capacity in the future. The international research collaboration network on FC is divided into 10 clusters, reflecting regional and thematic research orientations. This clustering structure offers insight into the global landscape of FC development and dissemination.

Table 1. Comparison of Countries' Contributions

Note: Data derived from VOSviewer analysis of co-authorship networks and citation patterns.

Figure 4. Citation-Countries Trend Map in Recent Years

Figure 4 illustrates the temporal evolution and level of international collaboration among countries involved in FC research. The color gradient in the map reflects the publication timeline, ranging from purple (pre-2019) to yellow (2023), while the size and thickness of the connecting lines indicate the extent of academic collaboration.

The period before 2020 is considered the foundational stage in which theoretical frameworks were shaped and academic centers on FC at the K-12 level emerged. Countries colored in purple to dark blue, such as the United States, Hong Kong, Taiwan, Australia, and Greece, were pioneers in implementing and researching FC in primary and secondary education. These countries recorded a high number of publications, strong citation performance, and significant academic link strength.

Post-2020, particularly during the COVID-19 pandemic, FC research rapidly expanded across various regions due to the urgent need to shift to online teaching. Countries shaded in light green, including Malaysia, Indonesia, Turkey, Canada, Spain, and the United Kingdom, marked a significant increase in publications and collaborative networks. Their research focused on the emergency application of FC in school settings, assessing its effectiveness under constrained conditions. Notably, Indonesia emerged as a regional hub in Southeast Asia, with numerous internationally co-authored publications, reflecting its initiative-taking adoption of FC in mainstream education.

From 2022 onward, FC research at the K-12 level has experienced global diffusion, with increased participation from newly emerging countries on the academic map, represented in pale yellow, such as Iran, Morocco, the UAE, Viet Nam, and the Philippines. This trend highlights the growing potential for developing robust research networks in developing countries amid the global shift toward digital education.

Influential Organizations

Figure 5. Map of Citation-Network Organization

(minimum number of documents per organization: 1)

Figure 5 and Table 2 depict the role of various organizations in the FC research network at the K-12 level. By examining metrics such as the number of publications, citations and TLS, the authors can identify the contribution and role of each organization. Prominent organizations with a TLS ≥ 60 are considered leading academic centers having a significant impact on the network. Department of Information Management (Taiwan) (TLS of 62) is the most influential organization, with superior citation and academic link metrics. The Faculty of Education at The University of Hong Kong (TLS: 61) is a top academic center in Asia, focusing on experimental research that applies FC in K-12 education and frequently collaborating with institutions in the UK, Australia, and Europe. The School of Computing and Information at the University of Pittsburgh (TLS: 62) is not only highly research-oriented but also plays a central academic role, connecting many other organizations and fostering the global dissemination of FC knowledge in K-12 education.

Table 2. Top 10 Most Influential Organizations

The bibliometric analysis by organization, combined with temporal factors, reveals a clear stratification in the formation and development of the academic network surrounding research on FC in K-12 education. It also reflects a shifting trend from foundational research institutions to emerging organizations in recent years (see Figure 6). The data is visualized using an overlay map generated byVOSviewer. The color spectrum represents the average time of citation for each organization:

*Dark purple (before 2018): Early influential organizations;

*Green (2019–2021): Organizations with steady, moderate influence;

*Light yellow (2022–2024): Emerging institutions with recently cited research.

Figure 6. The Formation and Development of the Academic Network

Influential Authors

Figure 7. Map of Co-Citation-Cited Authors (Minimum Number of Citations per Author: 20; 15,164 Authors Analyzed, 37 Meet the Threshold)

Figure 7 illustrates the co-citation network of authors in FC research, generated using VOSviewer. The analysis includes a total of 12,678 authors, with 85 authors meeting the minimum threshold of 20 citations. The co-citation map illustrates the frequency with which two authors are cited together in academic literature, thereby indicating their shared scholarly influence and intellectual connections. The size of each node represents the number of citations, while colored clusters denote groups of scholars with strong internal linkages. The network is divided into five major clusters, each representing a prominent research direction:

Red cluster (Cluster 1- Core influence center): This cluster features Bergmann and Sams (2012) as the most prominent node, highlighting their high citation frequency and role as pioneers of the FC model. Other key authors, such as Bishop and Verleger (2013), are recognized for significant contributions to the design and practical implementation of FC in education. Studies in the red cluster focus on identifying the fundamental principles and underlying concepts of the FC model, thereby laying a foundation for further research on the application of this model in educational practice. The Green cluster (Cluster 2) reflects the research trend of integrating technology into FC models. This group features Hew and Lo (2018) and Hwang and Chen (2019), who focused on integrating technology into FC, including areas such as e-learning, gamification, and artificial intelligence. The blue cluster (Cluster 3) focuses on instructional design and cognitive load reduction in FC to help students acquire knowledge more effectively with prominent authors such as Kapur (in Song & Kapur, 2017), Chen, N.-S.(in Wei et al., 2020). Authors in this cluster focus on studying strategies for designing lectures and learning materials to suit students' cognitive abilities, thereby reducing cognitive burden and optimizing learning effectiveness (Song & Kapur, 2017; Wei et al., 2020). The yellow cluster (Cluster 4) reflects studies on teacher adaptation and challenges in implementing the FC model. The trend-setting authors for this cluster, such as Roth, Glatt, Mayer, and Sweller, focused on studying the difficulties that teachers encounter when switching from traditional teaching methods to the FC model (Mayer, 2017; McLaughlin et al., 2014; Sweller, 2023). The purple cluster (Cluster 5) focuses on student satisfaction and active learning motivation in the FC model, with prominent authors including Zainuddin, Zhang, Li, et al. (2019) and Jong et al. (2022). Collectively, their work emphasizes FC's potential to foster active learning and enhance learners' personal responsibility.

Influential Studies

Table 3.Top 10 Most Influential Studies

This study employs bibliometric methods to identify and analyze the ten most influential works on FC at the K-12 level. These works are highly cited and pivotal in shaping theoretical frameworks, implementation practices, and effectiveness evaluations of FC in K-12 education. Among the top ten publications, Chen et al. (2014), Bhagat et al. (2016), and Lo et al. (2018) stand out. Chen et al. (2014) introduced the FLIPPED model, an expanded version of the traditional FLIP framework, which integrates components like flexible learning environments and student engagement. With 423 citations, this study is foundational in FC theory. Bhagat et al. (2016) demonstrated the positive impact of FC on academic performance and motivation, especially for low-achieving students. Lo et al. (2018) applied instructional design theory to FC, showing its benefits across subjects but noting variability in its effectiveness. Notably, studies by Bond (2020) and Wei et al. (2020) during the COVID-19 pandemic further emphasized the significance of active engagement and the efficacy of FC, especially for students of average ability.

Research Question 2: What Prominent Themes and Emerging Research Directions Can Be Identified Through Keyword Analysis?

In bibliometric analysis, examining keywords and research topics can reveal emerging trends and identify potential areas in the study of FC in K-12 education that remain underexplored. To address this question, the authors conducted a co-occurrence analysis of keywords and terms extracted from the titles and abstracts of data retrieved from the Scopus database. Keyword co-occurrence occurs when two terms appear together in the same article, indicating a conceptual relationship between them (H. K.Baker et al., 2020). This method was chosen because author keywords tend to accurately reflect the core content of the article (Comerio& Strozzi,2018).

Figure 9. Network Visualization Map of Co-Occurrence Keywords

(All Keywords with a Minimum Number of Occurrences of a Keyword: 3)

The co-occurrence analysis of keywords, based on 94 terms that appeared at least three times, revealed seven primary research clusters within FC in K-12 education. These clusters illustrate the thematic diversity and evolving research landscape of FC in K-12 education. Cluster 1 (Red)encompasses terms such as blended learning, educational innovation, and student engagement, with a focus on pedagogical innovation and the application of technology to transition from traditional to active and personalized learning models. Cluster 2 (Green) centers on controlled studies and experimental validations, comparing FC with traditional methods and assessing cognitive, motivational, and learning outcomes. Cluster 3 (Dark Blue)examines FC from the perspective of student capacity development, emphasizing active learning, self-efficacy, and motivation, often employing meta-analysis to evaluate effectiveness, particularly in subjects such as math and languages. Cluster 4 (Yellow) addresses the technical infrastructure supporting FC, such as digital learning systems and strategies for resolving pedagogical challenges. Cluster 5 (Purple) focuses on personalized, student-centered learning, particularly in primary schools, suggesting a promising area for future research. Cluster 6 (Light Blue) examines student satisfaction and learning outcomes, often integrating FC with project-based learning approaches. Finally, Cluster 7 (Orange) is an emerging area evaluating FC's impact on deep conceptual understanding in mathematics, with potential for future development.

In addition to keyword clusters, Figure 10 visualizes the density of keyword occurrences in FC research within K-12 education. The color scheme reflects levels of significance: Yellow: High density (core research topics); Green: Medium density (related fields); Blue and Purple: Low density (new or less explored research directions)

Figure 10. Keyword Density in Research on FC in K-12 Education

(All Keywords with a Minimum Number of Occurrences: 3)

The keyword "FC" appears 155 times, marking it as the central term in the map and underscoring its prominence in current educational research. High-density surrounding keywords, such as "flipped learning", "students", "teaching", "academic performance", and "high school", highlight the focus of current studies on implementing the FC model in general and secondary education to improve academic outcomes and enhance student engagement. The map’s gradient, ranging from dark blue to bright yellow, illustrates the wide-reaching interest in FC across various education levels and research methodologies. The presence of lower-frequency but strongly connected terms such as "meta-analysis", "self-efficacy", "project-based learning", and "student satisfaction" points to promising new avenues for future research.

Research Question 3: Which International Collaborations and Institutions Have Played Leading Roles in Advancing FC Research in K-12 Education?

International Collaboration

Figure 11. Co-Authorship Network Map by Country (Minimum Number of Citations per Country: 5; 57 Countries in Total, 15 Meet the Threshold)

Figure 11 illustrates that the United States is the dominant hub in the co-authorship network, with the largest node size and the highest number of connections, emphasizing its leadership in generating and sharing knowledge on the FC model globally. The U.S. collaborates extensively with countries across both Western and Asian regions, including Taiwan, the Philippines, Malaysia, Hong Kong, Australia, and the United Kingdom. Hong Kong stands out as a key connector between Western (Germany, U.S) and Eastern (Taiwan, Malaysia) nations, acting as a bridge for FC research collaboration.

The network reveals distinct regional collaboration clusters, each color-coded to represent a specific research group. The blue cluster, centered around the U.S., includes several Asian countries, showcasing strong trans-Pacific collaboration. The green cluster, involving Malaysia, Indonesia, and the U.K., highlights Southeast Asian cooperation, influenced by historical ties with British institutions. The yellow cluster highlights Hong Kong’s pivotal role in bridging the gap between the Eastern and Western academic communities. The red cluster, comprising Spain, Greece, and Australia, represents active collaboration between Southern European and Oceanian countries. Australia plays a pivotal role in linking multiple clusters, while Greece connects Spain and Australia. Germany and the Philippines, with fewer connections, show potential for future collaboration.

To further examine the inter-country links in FC in K-12 research, the study proceeds with a visualization that displays the average citation impact per country, along with citation-based interconnections among nations through scholarly publications.

Figure 12. Map of Citation-Countries (Minimum Number of Citations per Country: 1)

Figure 12 illustrates the uneven distribution of academic impact across countries. The United States has the largest node size, indicating it holds the highest number of citations in the field of FC. Other countries, such as Spain, Australia, Taiwan, Indonesia, and Hong Kong, exhibit significant node sizes, suggesting high citation counts and extensive academic connectivity both regionally and globally.

In terms of citation-based academic collaboration clusters (denoted by color): (a) The blue cluster includes the United States, Taiwan, Saudi Arabia, and Turkey, representing countries with strong academic infrastructures and high mutual citation influence. The U.S. serves as the central hub, with clear academic ties to both Asia and the Middle East; (b) The green cluster consists of Indonesia, Hong Kong, the Philippines, and Germany. This group reflects countries with increasingly prominent research activity in recent years, showing notable growth in citation volume and academic collaboration. Hong Kong and Indonesia act as active intermediaries within this cluster; (c) The red cluster, which includes Spain, the United Kingdom, Greece, Norway, and Australia, showcases the robust development of FC research in Europe and Oceania. Spain plays a significant role in this cluster, with numerous international connections.

Institutional Collaboration

Figure 13. Map of Citation-Organization (Minimum Number of Documents per Country: 1)

The analysis of institutional citation networks in FC research reveals varying levels of academic influence among institutions. The pink cluster is central, containing influential institutions such as the Faculty of Education at the University of Hong Kong. This group primarily includes faculties, research centers, and institutes focused on education, pedagogy, instructional technology, and language education, with a strong emphasis on empirical studies applying the FC model in K-12 education, HE, and teacher training. The green cluster highlights Asian institutions, including the University of Hong Kong, which integrate instructional theories with technology in FC research, bridging traditional Eastern education with global educational innovations. The red cluster focuses on teaching innovation, lesson design, assessment, and teacher professional development, with deep internal connections reflecting a practice-oriented academic ecosystem. The orange cluster represents institutions in computer science and learning technologies, such as the Department of Computer Science, which explores FC from a technological perspective. These institutions focus on developing learning management systems, designing digital materials, and analyzing learning data, thereby illustrating the integration of technology and pedagogy to create personalized learning experiences. Smaller institutions in the light purple and light blue clusters specialize in fields like linguistics, mathematics, and chemistry, contributing to FC research in specialized educational contexts, often through subject-specific studies or experimental research.

Conclusion

Research Development Trends

The bibliographic analysis in this study revealed that the period from 2014 to 2024 marked significant advances in FC research in K-12 education, particularly in terms of development trends, scope of influence, and prominent research directions. During the first three years (2014–2016), the number of publications was still modest, but it began to grow rapidly from 2019, peaking in 2023 with 56 articles. This surge is closely tied to the global shift toward online and blended learning driven by the COVID-19 pandemic, which created an urgent need for flexible and effective pedagogical models like FC (Bond, 2020). The increasing number of publications reflects a growing academic and practical interest in FC as a pedagogical model that can adapt to crises and support technological advancements in general education.

Influential Authors and Institutions

This innovative teaching model has garnered attention and recognition from educators and scholarsworldwide. However, the development of FC in K-12 education has not beenuniformacross countries. This study finds that the United States, Hong Kong, and Taiwan are the three most influential centers in the research network, as demonstrated by their high citation counts and strong collaborative links. These findings are consistent with the resultsof H.-L.TsaiandWu (2020), who studied FC from 2000 to 2019, andÇakıret al. (2021), who examined the period 2015-2019, both based on data from the Web of Science. The United States is considered the birthplace of the FC model in K-12 education (Bergmann & Sams, 2012;Yulita, 2024), and American scholars have authored many of the most highly cited publications. Hong Kong and Taiwan have emerged as leading hubs for experimental research in Asia (Hew & Lo, 2018), making their strong presence on the scientific map understandable. Countries such as Australia, Indonesia, China, and Malaysia alsoplay significant roles in regional connectivity, helping to establish a rich international collaboration network. Overall, while FC research in general education is being conducted globally, notable disparities and imbalances still remain.These findings suggest the need for policymakers and educators in less-represented countries to invest in research infrastructure and foster international collaboration to reduce geographic disparities in educational innovation.

In terms of institutions, institutions such as the Faculty of Education (The University of Hong Kong), the Department of Information Management (Taiwan), and the School of Computing and Information (University of Pittsburgh, United States) have been identified as the most influential centers, with high citation indices and central roles in global academic connectivity. Among them, the Faculty of Education at the University of Hong Kong not only generates academic knowledge but also plays a pivotal role in disseminating innovative pedagogical practices throughout Asia.

Although differing in database sources and research periods, the findings of the present study are entirely consistent with those of H.-L. Tsai and Wu(2020), who identified the three most influential institutions as originating from the United States, Hong Kong, and Taiwan. They are also partially aligned with the results of Lo and Hew (2017), which identified influential academic institutions on FC from the United States and Taiwan. This convergence indicates a relatively high level of agreement among studies in identifying key academic hubs on FC, reaffirming the leading role of institutions in the United States, Hong Kong, and Taiwan in shaping, disseminating, and advancing research trends on FC in K-12 education and pedagogical innovation at the global level.

Co-citation Analysis and Scholarly Ecosystem

The co-citation map highlights the most influential authors as Bergmann and Sams (2012), Bishop and Verleger (2013), Hew and Lo (2018), and Hwang and Chen (2019). While American authors primarily focus on foundational theory and model effectiveness, Asian scholars emphasize the integration of technology, learning outcome assessment, and pedagogical design. The clustering of authors into five distinct groups reflects the diversity of research orientations, ranging from theoretical to experimental and educational technology perspectives. Co-citation network analysis reveals that research on FC is currently shaped and advanced by a multi-centered academic ecosystem, with contributions from scholars across various academic cultures. Identifying influential author clusters, particularly central figures such as Bergmann and Sams (2012) and Bishop and Verleger (2013), not only confirms their leading roles in developing and disseminating the FC model but also offers a foundation for understanding the historical evolution and scholarly branching of this field. Authors from Asia, especially Hew and Lo (2018) and Hwang and Chen (2019), highlight the region’s growing role in driving tech-based educational innovation, paving the way for cross-regional, culturally adaptive comparative studies. This network structure provides educators with a clear reference map to identify core theoretical and practical works when designing teacher training or reforming instructional methods towards using the FC model in high school.

Foundational Publications and Pedagogical Impact

The top ten most-cited publications serve as foundational works in establishing theoretical frameworks, providing empirical evidence, and expanding the application of FC in K-12 education. Studies such as those by Chen et al. (2014), Bhagat et al. (2016), Lo et al. (2018), and Bond (2020) are not only highly cited but have also significantly influenced pedagogical approaches, school psychology, and curriculum design. These works represent a transition from evaluating effectiveness to expanding theory, from isolated studies to systematic reviews, and from subject-specific to interdisciplinary approaches. A noteworthy point is that most studies emphasize FC’s positive impact on fostering self-directed learning, active participation, and students’ positive subjective experiences. However, several challenges are also documented, including disparities in learning motivation, passive learning habits, and unequal access to technology among student groups.

Emerging Topics and Learning Innovations

Co-occurrence analysis of keywords reveals that the field of FC in K-12 education is evolving in an increasingly interdisciplinary and specialized direction. A notable trend is the emphasis on learner-centered education and personalized learning strategies, particularly at the primary level. This reflects a global shift toward a constructivist approach, where learners actively engage in knowledge construction through interactive activities, thereby fostering autonomy and self-directed learning. Research hotspots in the field of FC continue to exhibit a high degree of concentration. The main focus lies in the advantages of FC over traditional teaching methods, positioning it as an approach to enhance active learning, academic performance, learner engagement, and learning motivation. Readiness to learn is identified as a key factor for the success of FC. These findings align with ZainuddinandHalili (2016), who identified active learning and blended learning as two primary approaches within FC. According to the results, there is substantial indirect evidence suggesting that the flipped approach improves learning outcomes and student satisfaction. However, there is still a lack of compelling evidence linking it to the development of lifelong learning competencies and other 21st-century skills within K-12 education,and the low frequency of studies at the primary education level indicates a research gap that should be explored in future research trends (Lo et al., 2018).

Another prominent topic is the use of advanced technologies such as artificial intelligence and gamification to enhance the FC experience. Studies like Wei et al. (2020) andSergiset al. (2018) have demonstrated the value of integrating Self-Determination Theory and Cognitive Load Theory in evaluating the model’s effectiveness. A notable shift is the transition from a technical focus to psychological and cognitive aspects such as “self-efficacy”, “self-regulated learning”, and “student satisfaction”. This suggests that the research community is increasingly concerned with learners’ experiences rather than merely focusing on instructional design. Notably, keywords related to primary education, such as “primary school”, “student-centered learning”, and “collaborative learning,”remain sparse, indicating that this area continues to represent an underexplored frontier. Similarly, emerging research directions such as “conceptual understanding” and “gamification” point to future expansion opportunities, particularly in subjects like mathematics, science, and language learning.

The emergence of keywords such as “AI” and “gamification” signals a shift toward adaptive learning environments in K-12 education. These tools can be strategically integrated into teacher training programs to help educators personalize learning experiences and improve motivation through interactive digital tools. For instance, AI-powered platforms may support real-time feedback and differentiated instruction, while gamified learning modules can increase engagement in foundational subjects like math and science.

International Collaboration and Institutional Networks

Co-authorship maps reveal the clear formation of international collaboration networks in the field of FC in K-12 education. The United States holds a leading global role, with extensive connections across Asia and Europe. Hong Kong, Australia, Greece, and the UK serve as bridges between regional clusters, facilitating the dissemination of knowledge and the transfer of pedagogical practices. The structure of collaboration among research institutions also clearly shows a hierarchical pattern: from major academic centers to emerging research hubs in Southeast Asia. Notably, emerging institutions in countries such as Indonesia, the Philippines, Morocco, and Vietnam, despite having a limited number of publications, have started to appear within these networks, indicating the growth potential of developing nations. Participation in international networks not only enhances academic capacity but also promotes opportunities for future multilateral collaborative projects. Strengthening these networks through academic exchange programs or collaborative research grants could enhance both the scalability and contextual adaptability of FC practices across diverse education systems.

In conclusion, about the key findings: The bibliometric analysis of FC in K-12 education from 2014 to 2024 using Scopus data has provided a unique comprehensive picture of the rapid development and global spread of this model. By analyzing publication volumes, authors, organizations, countries, and keywords, the study indicates that FC is not merely a temporary trend emerging from the COVID-19 pandemic context but is gradually becoming an increasingly accepted pedagogical method, deeply integrated into education systems. Three key findings can be highlighted. First, the study confirms robust growth in both publication volume and citation rates, particularly from 2019 onwards, indicating a high demand for flexible, technology-integrated, and student-centered teaching models in educational practice. Second, a clear international collaboration network has formed, with leading academic hubs such as the United States, Hong Kong, Taiwan, and Australia playing a significant role in guiding and connecting global knowledge. Finally, the keyword analysis clarifies emerging trends such as self-regulated learning, student satisfaction, project-based learning, and the application of artificial intelligence, all of which demonstrate a shift from technical approaches to comprehensive, experience-based learning methods. Overall, this study not only contributes to the systematization of academic knowledge about FC in the context of K-12 education but also opens up directions for teacher training programs and improvements in education policy based on evidence. In the era of digital transformation and the globalization of education, FC has the potential to become a strategic foundation for improving teaching quality, promoting active learning, and developing well-rounded competencies for 21st-century students.

In addition to its academic contributions, the findings of this study have significant practical implications, providing recommendations for policymakers, researchers, teachers, and K-12 education administrators. For educational policymakers, identifying influential organizations and countries helps guide collaboration and learning from international experiences. Based on the findings, educational policymakers should focus on building and expanding international cooperation, learning from leading knowledge centers to improve the effectiveness of applying the FC model in K-12 education, particularly in developing countries where there are still many challenges related to infrastructure and technology. For researchers, the list of influential authors and publications serves as a foundation for further analysis on this topic. Researchers should continue to explore these influential authors and works on the application of the FC model in K-12 education, in order to develop both theoretical and practical studies suited to local contexts. Special attention should be given to trending topics on this subject within the most recent academic community. For teachers and school administrators, emerging research topics provide a basis for curriculum innovation, professional development, and designing more effective technology-integrated teaching activities. Identifying knowledge hubs, research gaps, and strategic directions for collaboration is essential for policymaking, teacher training, and the development of more effective K-12 curricula that meet the demands of 21st-century student competencies.

Limitations and Future Research Directions

Although this study provides a comprehensive overview of trends and the academic influence of the FC model from 2014 to 2024, several limitations should be acknowledged. To begin with, while Scopus was selected for its extensive collection of peer-reviewed educational research articles, other potentially useful academic sources, such as Web of Science, Google Scholar, and Microsoft Academic,were not included in the examined online database. To draw more comprehensive conclusions that better reflect publication trends in the field, it is recommended that future scholars expand their analyses using additional reputable datasets. At the same time, search strings need to be expanded to terms that are synonymous with the central keyword phrase. Future research should also consider other sources such as books, book chapters, and conference papers. This review's database only included English-language publications, thereby excluding non-English works that may offer more profound insights. Next, although tools like VOSviewer are useful for visualizing research patterns, they do not reflect the depth of content or methodological quality of individual studies. Future research should focus on: (1) Exploring under-researched topics such as FC in multicultural classrooms, or cultural context, learning behavior, and technology access as mediating variables that affect the success of FC in K-12 education. (2) Employing qualitative content analysis and systematic reviews to evaluate the implementation effectiveness of FC in specific contexts; (3) Establishing cross-regional research collaboration networks to enhance academic dialogue between developed and developing countries.

Institutional review board statement: Not applicable, as no humans or animals were used in this study. The data for this study originated from secondary desk research.

Informed consent: Not applicable. The data for this study originated from secondary desk research.

Competing interests: The authors declare no conflicts of interest.

Generative AI Statement

As the authors of this work, we used the AI tool ChatGPT for the purpose of language refinement and ensuring clarity in academic writing. After using this AI tool, we reviewed, edited, and verified the final version of our work. We, as the author(s), take full responsibility for the content of our published work.

Authorship Contribution Statement

Tieu: The conceptualization and design of the research, development of the research idea, literature review, VOSviewer software analysis, and drafting of the manuscript. Luu and Tow were responsible for data search and screening. Dao: Feedback on research concept and offered consultation regarding the search data. Nguyen: Data analysis, wrote the discussion section, organized and revised the manuscript, and provided final approval of the version to be published.