Research Trends of English Microlecture from 2013 to 2022: A Bibliometric Analysis

. English microlecture, as an emerging educational technology, has been widely used in educational practice and teaching activities with the rapid development of big data technology. Using data of journal articles on English microlecture from CNKI, this paper explored the research trends and hotspots in the field of English microlecture from 2013-2022, focusing on its application in education. It adopted a bibliometric analysis method to examine the publication trend, the highly cited publications, issuing institutions and hotspots. The research findings showed that the research on English microlecture was still in the exploratory period without a comprehensive and systematic research framework. Considerable attention had been paid to the issues concerning teaching level, teaching mode, teaching design and learning model. It was projected that English microlecture is expected to be established as a kind of systematic course and be applied more frequently in primary and middle school English classes.


1.Introduction
In recent years, innovative forms of technology education such as microlecture, MOOC and flipped classrooms have gained growing concern with the rapid development of information and communication technology. Microlecture, a micro-online video course, is a kind of online learning resources with specific instructional content. Featured with contextualization and flexibility, it is designed to teach or illustrate certain knowledge points such as key points, difficulties, doubts, etc., or to perform some teaching procedures, learning activities, experiments, tasks, etc. [1] .
In China, microlecture was first defined as an organic combination of various teaching resources which reflects teachers' teaching and learning activities focusing on a certain knowledge point or teaching procedure in the classroom teaching process, with video as the main carrier in accordance with the new curriculum standards and teaching practice requirements [2] .
Microlectures, characterized by brevity and conciseness, last generally 5 to 10 minutes in length, presenting fragmented learning content, processes, and extended materials around one key point. Consequently, microlectures are flexible and less restricted by time and space, considered as a curriculum resource that is easy to apply. Meanwhile, microlectures contribute to stimulating students' interest in learning, enhancing their motivation, and increasing their engagement. As an emerging educational approach, microlectures have attracted much attention for their wide implementation and application in different levels of educational settings.
Focusing on the application of English microlecture in education, the present study conducts a bibliometric analysis through CiteSpace software to review articles in the field of English microlecture published in domestic academic journals indexed by CNKI from 2013 to 2022 and investigate its status quo and future research directions.

Bibliometric Approach and Analytical Tool
In the process of big data development, a vast ocean of various literature is more accessible to reach, but also hard to be categorized and organized before being analyzed. In this way, the bibliometric analysis comes on the stage characterized with a quantitative analysis of the articles published in a specific field [3] . Bibliometrics was first proposed by Alan Pritchard, referring to "the application of mathematics and statistical methods" [4] . Nowadays, it has been applied in researches on publications in linguistics journals [5] , cognitive processing of emotional words [6] , and online discourse [7] .
CiteSpace is an information visualization software mainly used to measure and analyze scientific literature data [8] . It is mainly based on co-citation analysis theory and path finding network algorithm, etc., to measure the literature (collection) of a specific field, in order to explore the key paths of discipline evolution and the change of knowledge points it focuses on, and to perform the analysis of the potential dynamics of discipline evolution and the detection of discipline frontiers through a series of visual mapping [9] . Therefore, a quantitative research methodology was adopted for this study with the application of CiteSpace. Firstly, valid papers on China Knowledge Network were selected and downloaded in RefWorks format, and then uploaded to CiteSpace visual analysis software (6.1.r6) for data conversion and keyword co-occurrence. Segmentation year was adjusted to 1; setting criteria was set as g-index (k=25); control time region was chosen from 2013 to 2022.

Data Collection
In this study, the data were retrieved from China National Knowledge Infrastructure (CNKI), with a time span set between 2013-2022. To be specific, the search syntax "English, microlecture" were entered into the "Topic" section, both in English and Chinese, with category restricted to "Academic journals" and "Conferences". In order to enhance the relevance of the retrieved documents to the topic, articles with weak central relevance such as event announcements and news, were manually deleted. Furthermore, papers irrelevant to the topic were further checked manually by reading. Finally, a total of 2164 valid articles were obtained, of which 164 are from core journals. The upward trend of publications between 2013 to 2016 indicates that increasing attention had been paid to English microlecture in this period. Meanwhile, considerable emphasis had still been laid on this field from 2016 to 2019 when the number of publications remained above 300, even if there was a slight drop. Journal co-citations can be used to study the disciplinary basis of the field and its evolutionary analysis. Table 1 presents top 20 most highly-cited publications which could be generally categorized into three areas: application of microlecture in different education levels; effect and product development of microlecture from the perspective of teaching mode; learning model and microlecture design.

Most Highly Cited Publications
The two most influential articles focus on the development of microlecture itself and whether English microlecture could be used in classroom teaching, revealing the fact that microlecture is such an emerging teaching aid which has not been fully engaged in off-line teaching activities, and indicating that there is still a long way to go for researchers to thoroughly explore and apply it in classroom teaching. The author co-citation mapping can be used to analyze the scientific community within a field and its evolution [9] .

Most Highly Cited Authors
Cong Zhao [10][11][12][13][14] is the author who contributed most in English microlecture research, who mainly focuses on vocational English teaching, flipped classroom and medical English under the background of English microlecture application. Meanwhile, the result also exposes a comparatively average distribution that 1/4 of the authors published 2 articles and 2/3 of them only published one, indicating that the research on microlecture is still in the exploratory period and a comprehensive and systematic research framework has not yet been formulated.  As shown in Figure 2, the research on English microlecture in the past ten years has been mainly carried out in foreign languages departments of comprehensive universities and vocational and technical colleges. Few related outcomes have been generated by primary and secondary schools even if microlecture had been adopted in national English classes, because traditional teaching mode is still dominant in classroom teaching, reducing the opportunity for microlecture application. As for colleges, the number of articles issued by vocational and technical colleges is higher than that of foreign language schools in comprehensive universities, showing that English microlecture are more often used in vocational colleges and universities which emphasize practical exercises.  Keyword and cluster mapping is more helpful for identifying the hotspots and analyzing the evolution of them, especially with the presence of citation bursts [9] . Those that meet the threshold were extracted from the database. Top 15 most influential relevant topics are shown in Table 4. Besides, the map of keyword cluster is presented in Figure 3, with detailed information presented in Table 5.

Analysis of Hot Spots
From the keyword cluster and frequency distribution, four related research fields can be identified, contributing to further exploring the main issues that the popularity of English microlecture focuses on.

Education Level
At present, the application of English microlecture in junior high school and university classrooms is a research hotspot in this field.
Among all the learners, university students are the main targeted ones. As predicted by previous research, the advent of the "Internet +" era initiates a significant change in university English education that mobile English learning (2010-2013) has been transformed into one dominated by ubiquitous learning (2014 till now) with the support of self-media progression [15] . Compared with other levels of teaching, the teaching content of university education is highly specialized and the targeted subjects are from diverse educational backgrounds with a huge disparity in English proficiency, which illustrates why English microlecture serves as a useful teaching tool in university English education. Featured with brevity, conciseness, flexibility, and convenience, English microlectures can fully express a knowledge point within a limited time. Meanwhile, it is flexible for students to arrange previews and reviews according to their actual situation, which also contributes to the smooth progress of teaching procedures.
For junior high school English teaching, students are younger with less self-control and limited attention. The advantage of a short-duration of microlecture is in line with the characteristics of students' physical and mental development level, which contributes to keeping them interested in English learning. The entertainment experience offered by micro lecture could draw students' attention immediately, and enhance their learning motivation.

Teaching Mode
In the procession of "Internet+", microlecture technology has become increasingly mature, leading to a reform in the mode of education and teaching activities which appeals to a large number of scholars.
The "flipped classroom" is one of the new forms of teaching that meets the current needs of Chinese education by using microlecture as an extra-curricular aid. By extracting key points and difficult sections from a 45minute course content, an integrated microlecture within ten minutes is ready for students to preview. In addition, by adding supplementary materials, further explanations and extended analysis around the key knowledge of the microlecture, it becomes an accessible approach for students to preview and review lessons.
Zhang et al. [16] pointed out in the article Research on Flipped Classroom Teaching Model that in the flipped classroom, information technology and activity-based learning build a personalized and collaborative learning environment for learners, which helps form a new learning culture and promote the reform and innovation of teaching mode.
The emergence of "microlecture teaching" indicates that microlectures have been applied in classroom teaching. Drawing on microlecture as a part of classroom teaching procedure, its prominent feature of brevity and interest can attract students' attention and help them get immersed in studying more quickly. In the present situation, English teaching has been gradually integrated with modern education technology to create a new teaching mode.
"Microlecture" is a new teaching mode born in the era of "Internet+". Liang et al. [17] have argued that microlecture is not just a micro-video, but a systematic course with a complete set of teaching design. Therefore, it is obvious that microlecture is not only an emerging form of educational and teaching activities but also a professional and reliable teaching resource that meets the requirements of teaching design, albeit it is comparatively shorter in length and fragmented in knowledge.
At present, English micro-lessons have become an effective teaching approach. Whether directly played in the classroom or used as a supplement to classroom teaching, it has a significant impact on the form of educational teaching activities and boosts its development.

Teaching Design
With the widespread use of English microlecture in educational teaching activities, English microlecture design has gradually aroused a heated discussion in teaching design research. As an emerging educational tool, microlecture is still in the initial stage of development. Related exploration is in the stage of progress where their characteristics are identified, structural components are discovered, presentation forms are innovated, advantages are merged with theoretical knowledge, and the best suitable microlecture are designed to meet specific English teaching needs through a combination of theory and practice. Therefore, microlecture design is still one of the hot topics in this research field. In order to make microlecture better serve English teaching, it is also necessary to apply English pedagogy in the presence of microlecture. With continuous exploration and practice, a most elaborate design solution which gets the utmost out of the advantages of microlecture to meet the requirements of pedagogy is expected, in the hope of further creating a higher-effective classroom with satisfactory teaching quality.
The application of English microlecture has exerted a flurry of influences on traditional English classrooms. First, the classrooms become more interesting. The teacher's long-running lectures have been "broken up" by vivid and appealing microlectures, which drag students out of tedious and obscure illustrations by animating the dull explanation in textbook. Second, English teaching is no longer restricted by time and space. The classroom is no longer the only option where teachers could disseminate knowledge to students on account that they can present knowledge points or supplementary materials in a microlecture for students to preview before class or review after class. Considering microlectures as supplementary teaching methods, in-class time could be allocated to a specialized point or a single teaching procedure.

Learning Model
In addition to teaching mode, the impact of English microlectures on students' learning model is also one of the hot spots of research.
English microlectures could not only exert a beneficial impact on English learning but also offer an accessible approach for students to learning other knowledge. For example, if, in an elementary school natural science class, the teacher adopts an English microlecture to introduce science to help students learn encyclopedic knowledge, then the teaching language changes from their mother tongue to English, which may help shape students' learning model by acquiring encyclopedic knowledge in an English environment.
Meanwhile, the flexibility and convenience of microlectures create opportunities for students to arrange their own study schedule with learning resources provided. Instead of being confined to the classroom or restricted by time and space, students can obtain knowledge whenever they need to solve problems in daily life through English microlectures, which reveals the applicability mentioned in the learning model. Burst terms contribute to describing a process of dynamic change of hotspots and identifying research focuses in each period [9] . Keywords presented in Figure 4 were ranked as the top 6 ones mentioned most frequently and discussed most expressively in certain stages of English microlecture development. Research in the first period (2015-2017) centred around the emergence of microlecture, a latest educational application. From 2019 to 2022, research focus shifted to its wide range of application, and the teaching reforms and innovations it brought to classroom teaching.

The Emerging Educational Application
The period from 2015 to 2017 witnessed the boom of English microlecture, which made it a buzz word during this time.
Before 2015, English microlecturse had experienced three stages in the process of development: the structure of a microlecture, pedagogical practices in classroom, and being accepted as a systematic course delivery method [18] .
Therefore, period from 2015 to 2017 with English microlecture boom in high quality and reflected its value in education, which aroused the attention of general public, especially scholars and professors of linguistics and language teaching, and intrigued them to further explore the application of English microlectures. Researchers devoted themselves to improving the quality and quantity of English microlectures [19] ; teachers were trying to use it as supplementary teaching resources in university English education [20] ; psycholinguists attempted to establish new teaching modes with the application of English microlectures in the perspective of cognitive approach [21] .
In this phase, English microlecture, an emerging educational tool, had already been applied in certain fields and was still analyzed by researchers for future application.

Wide Range of Application
The year 2019 witnessed the wide range of application of English microlectures, drawing attention to tertiary education English, middle school English and primary school English. The research primarily focused on university education, and then gradually moved to primary and secondary education. At the end of 2022, the application of English microlectures in teaching activities at different education levels was still the main research subject, indicating that various experts and scholars were still looking for more optimal solutions to applying English microlecture in teaching to facilitate teaching and learning activities.
English microlectures were used in different education levels. In terms of primary school English, considerable emphasis was put to integrating the application of English microlectures with the practice of language pedagogy, such as situational language teaching, cognitive teaching and total physical response. However, in middle school English teaching, the focus shifted to the application of English microlecture in different sections in English learning, such as reading, speaking, listening and writing. What' s more, the research direction of its application in tertiary education English crossed the disciplinary boundaries. Scholars in universities attached so much importance to information literacy that they were engaged in exploring how to cultivate interdisciplinary talents as English microlecture were applied in classroom teaching.
Moreover, English microlectures were also used to boost the development of other modern education technologies. From 2019 to 2022, English microlecture served as one teaching step in some English classes, which means it was not only a short video presenting some knowledge points but also a platform for students to interact with teachers, raise questions, and receive feedback. In this way, new teaching technologies like MOOC and Flipped-classes managed to progress with the help of microlecture as a useful tool.
It is foreseeable that in the future, English microlecture would expand its application range and fill the existing research gap as it continues to conduct teaching activities with other modern technologies and be applied in all education levels.

Teaching Reforms and Innovations
During the period from 2020 to 2022, the goal of implementing curriculum-based moral education and stratified teaching has been given the priority in language teaching activities, aiming to boost students' all-round development while displaying their individual potential. This teaching objective calls for reforms and innovations in both teaching modes and learning models, which could be achieved by the flexibility of English microlectures.
Curriculum-based moral education, an educational philosophy that takes strengthen morality and forester talents as its fundamental task [22] , presents how English microlectures have changed the traditional teaching mode that teachers dominate the classroom education by giving long lectures without allocating time to student activities. Nowadays, students are the center of classroom teaching. To inspire students' learning motivation, a tedious class lecture is substituted with a concise English microlecture; to enhance students' problem-solving skills in reality, a literally text analysis gives way to learning from English microlectures depicting scenes of life. Obviously, featured with flexibility, English mocrolectures manage to prioritize students' needs in classroom teaching and give the initiative back to them by boosting the formation of new teaching modes.
The development and implementation of stratified teaching are based on the flexibility of microlectures, which has been studied for only two years and is less intensive, leaving a flurry of opportunities for development. Uploaded to an open platform available to all students in a class after recording teachers' explanation about key points of a certain knowledge, English microlectures serve as learning materials with high flexibility which could be obtained at anytime and anywhere, breaking the limitation of time and space. This salient characteristic not only contributes to shaping a new learning model, but also generates an emerging teaching mode, the stratified teaching. Endeavoring to promote students' personalized development, the model of stratified teaching is in line with the concept of humancenteredness advocated by the New English Curriculum Standards for Junior and Senior High Schools (referred to the New Standard hereafter) [23] .
During this phase, the traditional English microlectures have been gradually turned to a kind of independent online micro-course, which could not only create a more efficient teaching paradigm but also shape a more effective learning mode. To be more specific, English microlectures serve as convenient tools for teachers to adjust their teaching design and procedures in accordance with students' needs and also an accessible approach for all students to a vast ocean of learning materials provided by other countries in our international community due to globalization. Overall, the flexible English microlecture has managed to create diverse teaching modes to guarantee every student's selfimprovement and personal learning model to enable all students to acquire enough knowledge in their own pace, and further realize the concept proposed by the New Standard.

4.Conclusion
This paper focuses on the application of English microlectures in education and teaching activities, exploring its hotspots and predicting future research direction in this field. Based on the bibliometric research method, it analyzes the status quo of English microlectures in terms of publication trend, the most highly-cited publications, the most highly-cited authors, issuing institutions, keywords and development trends by CiteSpace with data resources collected from CNKI. The findings reveal that English microlectures have played an important role not only in the teaching and learning field but also in promoting teaching reform alongside the development of "Internet+".
The findings also show that the past decade has witnessed a huge progress in researches on microlectures with more than 2000 papers published, and 2016 is the most fruitful year with over 400 publications. However, a comprehensive and systematic research framework has not yet been formulated since there are few productive authors or issuing institutions.
What's more, the current research hotspots centred around four fields: teaching level, teaching mode, teaching design, and learning model. English microlectures are mainly applied in junior high schools and universities, served as an effective teaching approach and also supplementary teaching resources. In the process of application, students' learning model has been reshaped as a kind of self-directed learning. In terms of the development trends, English microlecture has been improved in quality and quantity, selected as a procedure in teaching and become a systematic course delivery method now. Based on all results mentioned above, it is projected that English microlectures may be further established as an independent course with expanding application in primary and secondary school teaching activities, fitting in with the requirements of the new curriculum.
However, since all data resources are extracted from CNKI, only China's literature has been analyzed. More data from international academic circle are needed in the future research.