A Trend Analysis of Research on the Flipped Classroom in L2 Learning before and after COVID-19 "2279

The aim of this research is to examine the EFL flipped classroom trend before and during COVID-19 by the frequent types of research designs and topics investigated in the studies. For this purpose, a content analysis was used as the research methodology. A content analysis was implemented for each article regarding research design and subject. A total of 44 research papers from journals listed in the Social Sciences Citation Index (SSCI), Education Resources Information Center (ERIC), Springer, and Scopus were analyzed. Only recent studies between 2017 and 2021 were reviewed because this study aims to analyze papers published immediately before and after the COVID-19 outbreak. First, the results showed writing skills were investigated more than speaking and listening skills. Next, the flipped classroom positively affected EFL learners’ writing, grammar, and speaking anxiety. In addition, the most commonly used research method was the mixed method (n = 25), and the least used was the qualitative method (n = 3) during the years 2017–2021. The findings also revealed that the trend decreased from 2017 to 2018; however, it increased rapidly after 2018. This paper implicates that the recent research trend on flipped classrooms during emergency online L2 education focused on EFL writing, more research is needed to examine other language skills.


Introduction
A flipped classroom is an instructional strategy and a type of blended learning that aims to change the traditional classroom model upside down and emphasizes effective use of class time. The flipped classroom instructional strategy is defined as students using instructional videos and supporting materials before attending class, and then during lessons they engage in collaborative and interactive learning activities [1]. It allows lessons to be student-centered instead of teacher-centered. Flipped classrooms are attracting growing concern all over the world, and it has become the focus area of teachers (e.g., Güvenç [2] and Mubarok et al. [3]). For example, when the teacher flips the classroom s/he video records his/her lessons at home and assigns them to students as homework. The learners come to class prepared the next day and do their homework or assignments in class. This approach allows learners to become more interactive and motivated, and it allows them to work at their own pace. While they are doing their assignments in class, they have their teachers to guide them. The teacher at this point is the one that guides and shows the learners how to do things. It allows learning to be carried out of the classroom into everyday life. The flipped classroom approach allows learning to take place everywhere and not just in class. The students can watch the lectures at home, get prepared before class, and receive help from their teachers during the lesson. Next, teachers can free up time and help students individually in the flipped classroom (Basal, 2015). Furthermore, the flipped classroom can activate learners, increase their passion, allow autonomous learning, and create a learner-centered classroom. The flipped classroom involves the principles of constructivism, student-centered instruction, and different types of learning strategies. It is personalized because every student can work at their own pace and receive and understand the input according to their needs [4]. In addition, flipped classroom and flipped learning have different meanings. A flipped classroom creates texts, lectures, and courses that can be read at a student's own pace. On the other hand, flipped learning is the combination of face-to-face education with online learning.
There are several studies on the flipped classroom and its effects on EFL learners; however, there is a lack of research comparing the flipped classroom trend before and during COVID-19. A content analysis was used to collect all the relevant data from different perspectives and to analyze the frequent types of research designs used and topics investigated when analyzing the effects of the flipped classroom in an EFL classroom. In addition, the trend of the flipped classroom before and during emergency online education will be shown. The trend in research will show whether the amount of research increased or decreased during the pandemic. After the COVID-19 outbreak, institutions switched their education to emergency online education. Although several studies have investigated the use of flipped classroom approach in online classrooms [5][6][7][8], almost no studies investigated the L2 education in an emergency online context. There were many studies before the pandemic on the flipped classroom. However, it is possible to see that publications increased during the pandemic. Making a synthesis of the papers may help guide future research, and it could help researchers determine their research headings and topics. Therefore, this study aims to bridge this research gap [9,10]. The current study is significant in the field because it provides a content analysis of the findings from previous studies in the literature, which can help future studies and give researchers insight.

Distance Education and Flipped Classroom
In 2019 an infectious disease called coronavirus spread throughout the world. Coronavirus affected people in different ways. It affected every sector in the world as well as education. Countries started to implement distance education to avoid contact among people. This lack of interaction, of course, resulted in anxiety and stress in learners, parents, and teachers (Bailey and Lee 2021). Most countries were not ready to provide online education, but they had to take action because no one had another option.
Due to COVID-19 schools were shut down and emergency remote education had to be implemented. For example, Nerantzi [11] conducted a study to evaluate which strategies, flipped learning or peer instructions, were relevant during COVID-19 and provide practical advice to teachers. The researcher underlined the fact that flipped learning and peer instruction are similar, where both approaches allow learning outside the classroom. Institutions want learners to participate actively in their courses; therefore, Nerantzi [11] concluded that flipped learning and peer instruction should be considered.
Harida et al. [12] investigated the perceptions of EFL learners about online learning, together with flipped classroom learning. A descriptive method was used to explain the perceptions of the learners. A total of 32 students studying in the English department participated in this research. At first when the students were interviewed, they did not know anything about the flipped classroom approach; therefore, they did not feel comfortable with distance learning and preferred face-to-face education. However, they reacted positively and were more interested when the approach was introduced and implemented. It is therefore possible to state that using the flipped classroom approach during distance education positively affects students' achievements and motivation. Similarly, Ramadhanty et al. [10] investigated the experiences of EFL learners using the flipped classroom during the pandemic era. The students faced several challenges; however, the results showed that learners had a positive attitude toward the flipped classroom experience.
Guessabi [13] conducted a study to present the use of flipped classrooms in higher education during the pandemic. Before COVID-19, students and lecturers in higher education in Algeria were against the flipped classroom approach. From the data collected, however, Guessabi concluded that lecturers started to use the flipped classroom approach due to distance education because they did not have another option.
Sumardi et al. [14] conducted a study to analyze the challenges of implementing English remote teaching (ERT)-based instruction to promote students' engagement during instructional practices. The ERT-based instruction followed the flipped classroom approach, where videos are uploaded before the lesson and class group discussions take place during the lesson. A total of 17 preservice teachers participated in this study. The results revealed that most of the teachers thought ERT helped them during this period and that there were no significant obstacles. In addition to the above research, Sarani et al. [15] conducted a study from another perspective. The researchers investigated the effects of the flipped classroom on EFL students' writing skills. The results showed that the experimental group outperformed the control group. Therefore, it is possible to state that the flipped classroom positively affects student writing even if it is conducted through an online course.
The research conducted during the pandemic on flipped classrooms were limited; however, it was not impossible. Several studies investigated the flipped classroom approach [12][13][14]. As seen from the results of the studies, using the flipped approach during distance education has similar results to the studies conducted face-to-face. For example, the experimental group generally outperformed the control group. Furthermore, implementing the flipped classroom online affects student performances and motivation positively [12,15].

Online Education vs. Distance Education
In 2019 the norms of the world changed due to COVID-19. Since this disease was very risky and dangerous, every country around the world was forced to change to distance education where face-to-face lessons and interaction with students were banned. Before the pandemic, everyone knew about the term 'online education'; however, with COVID-19 the term 'distance education' started to appear.
Online education allows learners to interact with their teachers in person regularly. It is a blended-learning technique. While some of the lessons are online the teacher still has the opportunity to implement a face-to-face lesson.
On the other hand, distance education does not allow interaction between the teacher and the student. Teachers are only able to teach their learners via online platforms. IN person interaction does not take place in any form. For example, before the pandemic outbreak, the flipped classroom approach was frequently linked to online education [5,6], and almost no studies have investigated the flipped classroom use in distance education.

Research Questions
This study aims to answer the following questions about studies focusing on the flipped classroom approach: RQ1 What are the frequent types of research used to investigate the effects of the flipped classroom on EFL learners? RQ2 What are the frequent topics investigated in the reviewed studies? RQ3 What is the trend of the flipped classroom approach used before and during the COVID-19 pandemic?

Research Design
A content analysis research design was followed in the current study. Written materials are frequently analyzed using content analysis. It is a systematic and objective approach to describing and characterizing phenomena as a research method [16]. "Content analysis can be divided into meta-analysis, metasynthesis (thematic content analysis), and descriptive content analysis" (p. 121, [16]). Thus, this review aims to gather well-documented sources from published work to identify the research designs used, topics discussed, and the trend of the flipped classroom approach between the years 2017-2021. In addition, findings from previous research on the same topic were taken into account and analyzed. Finally, after several papers were analyzed and synthesized, the conclusions of these papers were reported to answer three research questions of this paper.

Data Collection
A total of 44 research papers published between 2017 and 2021 were analyzed for this content analysis. Only articles published in the journals listed in the Social Sciences Citation Index (SSCI), Education Resources Information Center (ERIC), Springer, Scopus, and DOAJ were analyzed. Only these journals were chosen because they were high-quality journals when data accuracy, validity, and reliability were considered. The researchers first looked into Web of Science indexed journals since it was the largest one compared to the other journals. The publication date was marked 'since 2019' on the sites to find research papers conducted during COVID-19, The keywords used included "flipped classroom", "flipped learning", "EFL", and "COVID-19" to find the research papers. The papers employed various types of research designs and methodologies. The articles that focused on the effects of the flipped classroom on EFL learners' writings, speaking, and grammar were chosen and analyzed. Papers that were not accessible and written in languages other than English were excluded.

Data Analysis
Each article was analyzed and reviewed in terms of research designs, topics discussed, and the year of publication. The results were descriptively analyzed and shown using bar graphs and line graphs. A table showing the year of publication, journal name, index, and impact factor have also been included.

RQ1
: What are the frequent types of research used to investigate the effects of the flipped classroom on EFL learners?
A total of 44 research papers were analyzed to answer Research Question 1. In addition, the effects of the flipped classroom approach on EFL learners' writing, speaking, listening, and achievements were analyzed using different types of research designs.
As shown in Figure 1, the most commonly used research method was the mixed method (n = 25), followed by the quantitative method (n = 14). The qualitative method (n = 3) was the least used for this research topic between 2017 and 2021. When considering the years, it can be seen that during 2017 and 2018, mixed-method and quantitative methods were used for data collection. During 2019-2021 all four research methods were used; however, the mixed research method was used more than the other types.
RQ2: What are the frequent topics investigated in the reviewed studies?
The researchers reviewed the papers to identify the topics of the studies between 2017-2018 and 2019-2021. As shown in Figure 2, the most common topic researched in the studies was the effects of the flipped classroom on EFL learners' writing skills (n = 12). The second most researched topic was speaking skills (n = 9), followed by listening skills (n = 3) and the success of the learners (n = 5). Finally, the topics researched under "other" were grammar skills, learners' perceptions of the approach, self-regulation, and the effects of learner autonomy. In addition, the number of studies conducted on the impact of the flipped classroom on EFL learners' writing skills was higher during 2019-2021 compared to 2017-2018. Therefore, the column named 'other' is higher than the other topics; however, it is essential to note that four different topics were investigated under the 'other' column.  Figure 2, the most common topic researched in the studies was the effects of the flipped classroom on EFL learners' writing skills (n = 12). The second most researched topic was speaking skills (n = 9), followed by listening skills (n = 3) and the success of the learners (n = 5). Finally, the topics researched under "other" were grammar skills, learners' perceptions of the approach, self-regulation, and the effects of learner autonomy. In addition, the number of studies conducted on the impact of the flipped classroom on EFL learners' writing skills was higher during 2019-2021 compared to 2017-2018. Therefore, the column named 'other' is higher than the other topics; however, it is essential to note that four different topics were investigated under the 'other' column.  RQ2: What are the frequent topics investigated in the reviewed studies?
The researchers reviewed the papers to identify the topics of the studies between 2017-2018 and 2019-2021. As shown in Figure 2, the most common topic researched in the studies was the effects of the flipped classroom on EFL learners' writing skills (n = 12). The second most researched topic was speaking skills (n = 9), followed by listening skills (n = 3) and the success of the learners (n = 5). Finally, the topics researched under "other" were grammar skills, learners' perceptions of the approach, self-regulation, and the effects of learner autonomy. In addition, the number of studies conducted on the impact of the flipped classroom on EFL learners' writing skills was higher during 2019-2021 compared to 2017-2018. Therefore, the column named 'other' is higher than the other topics; however, it is essential to note that four different topics were investigated under the 'other' column. RQ3: What is the trend of the flipped classroom approach used before and during the COVID-19 pandemic?
The publication years of the analyzed studies are recorded on a chart in Figure 3. Papers between 2017 and 2021 were analyzed to determine the number of papers published on the flipped classroom approach before and during COVID-19. The figure above shows the distribution of studies conducted on the flipped classroom. The number of studies in 2017 was high (n = 8); however, the publication rate decreased in 2018. In 2019 and 2020, the numbers started to increase again. In 2020 schools ended face-to-face education and implemented emergency online education due to the COVID-19 pandemic. Even though the world was facing a pandemic, several research papers were published, and researchers could conduct their research on the flipped classroom approach with emergency online education. Since the cut-off date was June, only 10 articles were included from 2021. of studies in 2017 was high (n = 8); however, the publication rate decreased in 2018. In 2019 and 2020, the numbers started to increase again. In 2020 schools ended face-to-face education and implemented emergency online education due to the COVID-19 pandemic. Even though the world was facing a pandemic, several research papers were published, and researchers could conduct their research on the flipped classroom approach with emergency online education. Since the cut-off date was June, only 10 articles were included from 2021. In Table 1, studies published before the pandemic are shown. It provides details about the papers analyzed and reviewed. The purpose, study design, sample size, and results of the articles analyzed are presented precisely. The number of participants ranged between 22 and 189. As shown in Table 1, the flipped classroom approach positively affects EFL learners, and students have a positive attitude toward this approach.  [17] Investigating the impact of flipped instruction on students' foreign language writing skill.

Mixed Method 23
Students in the experimental group outperformed the students in the control group.
Boyraz, S., and Ocak, G. (2017) [18] Examining the effects of FC on academic success and retention of knowledge as well as learners' opinions on this approach.

Mixed (Quasiexperimental) 42
The FC approach had a positive effect on learning compared to the traditional approach.
Amiryousefi, M. (2019) [19] Investigating the effects of flipped learning on EFL learners' L2 speaking, listening, and out-of-class participation and engagement with course materials and activities.

Mixed Method 67
Flipped learning can help EFL learners improve their L2 speaking and listening. In Table 1, studies published before the pandemic are shown. It provides details about the papers analyzed and reviewed. The purpose, study design, sample size, and results of the articles analyzed are presented precisely. The number of participants ranged between 22 and 189. As shown in Table 1, the flipped classroom approach positively affects EFL learners, and students have a positive attitude toward this approach. Ekmekci, E. (2017) [17] Investigating the impact of flipped instruction on students' foreign language writing skill.

Mixed Method 23
Students in the experimental group outperformed the students in the control group.
Boyraz, S., and Ocak, G. (2017) [18] Examining the effects of FC on academic success and retention of knowledge as well as learners' opinions on this approach.

Mixed (Quasi-experimental) 42
The FC approach had a positive effect on learning compared to the traditional approach.
Amiryousefi, M. (2019) [19] Investigating the effects of flipped learning on EFL learners' L2 speaking, listening, and out-of-class participation and engagement with course materials and activities.

Mixed Method 67
Flipped learning can help EFL learners improve their L2 speaking and listening.
Köroglu, Z.Ç., and Çakır. A (2017) The effects of flipped instruction on preservice English language teachers' speaking skills development.

Quantitative data 48
The experimental group outperformed the control group.
In addition, the FC positively affected the learners' fluency, pronunciation, grammar, and coherence skills.

Quantitative 40
After implementing the flipped classroom, the learners' English scores were higher, they were satisfied with the approach, and they also became autonomous learners.

Mixed Method 60
The FC model of instruction positively affected the learners' reading comprehension skills. In addition, the learners also developed a positive attitude toward this approach.

Author, Year Purpose Study Design Sample Target Population Findings
Kurt, G. (2017) [22] Examining the effectiveness of the flipped classroom compared to a traditionally taught class.
Mixed (Quasi-experimental) 62 pre-service teachers (PTs) The FC had better learning outcomes and a higher self-efficacy than the control group. The PTs also had a positive attitude toward this approach.

Mixed Method 61
The learners in the flipped classroom fostered autonomous learning and peer interaction. They could control their learning outcomes, were better with online activities, and their intrinsic motivations increased.

Mixed Method 40
Implementation of the flipped classroom improved peer collaborative dialogue among learners.
Quantitative 55 FC has a positive effect on learners' writing quality.

Mixed Method 48
Learners had a positive attitude toward this approach, allowing cross-cultural observation to occur.
(2019) [25] Examining how flipped classroom promotes active group writing and effective learning from peers.

Mixed Method 66
The results of the experimental group were higher than the control group.

Mixed Method 66
The students in the experimental group had higher scores on writing tests than the control groups. In addition, most of the learners had a positive attitude toward this approach.

Quantitative (Pre-experimental design) 95
The results showed that the experimental group outperformed the control group. There was also a significant difference in learners' willingness to communicate between the two groups.
Abdullah, M.Y., Hussin, S., and Ismail, K. (2019) [27] Examining the effect of implementing the flipped classroom model (FCM) on the motivation level of Omani EFL learners to speak English.

Mixed Methods (Quasi-experimental) 27
Findings showed that implementing the flipped classroom approach helped develop a creative, engaging, and motivating climate in the EFL speaking class. FC also increased learners' motivation in speaking.

Quantitative (factorial quasi-experimental) 58
The results showed that the experimental group had a higher score than the control group.
Yang, C.C.R., and Chen, Y. (2019) [28] Investigating the effectiveness of using the FCM in teaching English vowels and perceptions of the learners and the teachers toward the flipped classroom.

Mixed Methods (Quasi-experimental) 189
The learners in the flipped classroom had shown a gain in knowledge of the lesson topic taught. In addition, the findings also showed that there was not a significant difference between the two groups' posttests.  [29] Examining the effects of the flipped classroom model on EFL learner autonomy in a content-based instructional context.

Quantitative 124
The flipped classroom positively affected learner autonomy, learner behavior, and learner confidence. In addition, learner autonomy was improved in terms of interaction with materials, behavior, and self-management strategy of learning and the use of social resources.

Mixed Method 22
FC enhanced speaking skills, and it also increased learners' motivation.

Quantitative data 60
The FC had a positive impact on the learners' pragmatic competence and the learners enjoyed learning English Table 2 shows studies published during the pandemic. The results revealed that it is possible and effective to use the flipped classroom approach during distance education (Çil, 2021) [10]. Unfortunately, only 10 research papers from 2021 were included due to the cut-off date of this study. Altas, E.A., and Mede, E. (2020) [32] Investigating the impact of the flipped classroom on preservice English teachers' advanced writing achievements.

Mixed Method 55
FC approach had a positive impact on writing skills; however, self-regulated learning showed no difference.

Qualitative 18
The learners had a positive attitude toward the approach. It was also found that the flipped approach supported the learners positively.

Mixed (Quasi-experimental) 51
The flipped classroom outperformed the nonflipped classroom on EFL students' writing performance and fluency.

Quantitative (Experimental study) 53
The flipped classroom outperformed the nonflipped classroom in grammatical competence and writing skills.

50
Teaching writing using a flipped approach instruction model through the WhatsApp group reveals itself to be more effective than the individual one.
Alghasab, M.B. (2020) [37] Investigating the pedagogical benefits for the development of writing skills of EFL learners.

Qualitative 30
Results revealed that the flipped classroom positively affected learners' writing skills. Next, the learners also had a positive attitude towards this approach.  [38] Examining the effect of this flipped learning approach on raising Iranian EFL learners' self-regulation.

Mixed Method 26
Learners taught with the flipped approach were more aware of the learning process and had fun, which allowed them to develop self-regulated learning.
Quantitative 58 The flipped classroom approach increased learners' self-efficacy. In addition, when gender was considered, it was found that the female learners' self-confidence increased compared to the males.

Mixed Method 40
Using the flipped classroom positively affected EFL learners' listening comprehension and critical thinking skills.

Quantitative 384
The learners in the flipped classroom received higher exam scores than the nonflipped students.
Al-Naabi, I.S. (2020) [42] Investigating the impact of flipped learning on Omani EFL learners' grammar and examining students' perceptions of the flipped classroom.

Mixed (Quasi-experimental) 28
Implementing the flipped classroom had a positive effect on learners' grammar knowledge. In addition, the learners also developed a positive attitude toward this approach.
(2020) [43] Examining the trends and main findings of the studies concerning the flipped classroom method in the field of English Language Teaching (ELT).

Literature review
The findings revealed that the flipped classroom had benefits on EFL learners. Speaking and writing abilities were the most commonly studied language skills.

Mixed Methods 27
The findings showed that speaking anxiety levels of learners decreased.
Öztürk, M., and Çakıroglu, Ü. (2021) [44] Examining the development of students' language skills in a flipped EFL course designed with self-regulated learning strategies.
Mixed (Quasi-experimental) 49 Self-regulated learning had a positive effect on EFL development in a flipped classroom model.

Mixed Method 40
Using a WebQuest-based flipped classroom had a positive effect on learners' inferential reading comprehension skills.

Mixed Method 40
The learners preferred the flipped classroom over the traditional one.
Afzali, Z., and Izadpanah, S. (2021) [47] Examining the effect of the flipped classroom model on learners' engagement and motivation in learning English grammar.

Mixed (Quasi-experimental) 360
Learners in the experimental group showed an increase in their performance on grammar tests. They also developed a positive attitude toward grammar and were more motivated.
Khoiriyah (2021) [48] Investigating the effect of the flipped classroom on EFL learners' listening skills. It also explored the learners perceptions toward the flipped classroom approach.

Mixed Method 51
The results showed that implementing the flipped classroom enhanced learners' listening skills. In addition, learners had a positive attitude towards the approach.
Examining the strengths, weaknesses, and effectiveness of the flipped classroom with CALL in EFL writing class.

Mixed Method 150 learners and 14 teachers
The results showed that implementing the flipped classroom with CALL has many advantages, and the results also revealed that it had a positive effect on learners' writing skills.

Quantitative Method 67
The results revealed that the learners taught in the flipped classroom outperformed the learners taught in the traditional classroom.
Mixed (Qualitative and descriptive) 9 students The learners had a positive attitude toward this approach; however, students faced some challenges.
Quantitative (Descriptive study) 32 Students showed a positive perspective on flipped learning. Çil, O. (2021) [10] Investigating the perception of preservice elementary school teachers on the flipped classroom approach.

Qualitative study 53
The results showed that the flipped classroom approach was efficient during distance education.
Sumardi, S., and Nugrahani, D. (2021) [14] Investigating the use of flipped classroom in higher education. Case study (qualitative) 17 pre-service language teachers ERT has successfully replaced face-to-face education; however, there were also some challenges: low achieving students had problems dealing with the situation by themselves.

Discussion and Conclusions
The flipped classroom approach is not a new phenomenon and has been popular for more than a decade. In 2020, however, circumstances changed when COVID-19 started to spread. This study analyzed 44 research papers published between 2017-2018 and 2019-2021 by different variables such as research topics, research methods, participants and publication year. This topic was chosen because there is a lack of research comparing the flipped classroom trend before and during COVID-19. Only papers published in the journals listed in the Social Sciences Citation Index (SSCI), Education Resources Information Center (ERIC), Springer, Scopus, and DOAJ were analyzed. The analyses showed that since 2019 the number of articles published on the flipped classroom method increased, and in 2020 there was a sharp rise in research on the flipped classroom. The amount of research on this approach is increasing daily and is becoming a primary focus of researchers [34]. The increased number of research papers could be linked to the method's growing popularity and the benefits it provides. It can be seen that there has been a lot of interest in the topic in the last three years, which indicates that it will grow in popularity in the future. Even though the world was facing a pandemic during 2020, the number of publications did not decrease After analyzing the research methods used in the studies, it was possible to note that the mixed research method was the most commonly used when researching the flipped classroom, followed by the quantitative research method. The results revealed that EFL learners had a positive attitude toward this approach. Implementing the flipped classroom approach while teaching writing, speaking, and grammar positively impacted learner results. Learners taught in the flipped classroom outperformed those taught traditionally [24,47]. Using the flipped classroom approach motivates learners, allows them to learn at their own pace, and allows them to interact [3]. The study of Abdulla et al. [27], claims that learners developed a positive attitude toward this approach, positively affecting their motivation to speak English.
The distribution of the published articles between 2017 and 2021 appears to be reasonably close to each other. Only during 2018 was the number of publications low compared to the other years. Due to the pandemic, schools started to teach online, which forced researchers to conduct their research online. The research trends showed that the number of studies during the pandemic was high, allowing researchers to conduct their research online (in and out of class). The quantity of research conducted in 2021 seems low; however, that is due to the cut-off date of this research paper (which was June 2021). The results indicate that not every student was happy about the flipped classroom approach and online education. They prefer handout worksheets rather than PDFs [13]. Implementing the flipped classroom during an online period also had some challenges such as internet and technical problems. However, teachers were positive about using the flipped-classroom approach to teaching [14].
Educators can use this approach to teach EFL learners because this approach allows learners to progress at their own pace, and it helps them acquire the required information slowly and carefully. The findings of this study can provide the teacher-researchers with ideas on using this approach in their classrooms. Based on the findings, the flipped classroom has many advantages for learners and positively affects them. In addition, implementing the flip classroom allows more interaction between the teacher and student, which later on results in a strong relationship resulting in better results [49].
Some researchers underlined that implementing the flipped classroom also has disadvantages in other literature. For example, some students may not have a computer or access to the internet, which will cause a problem for both the teacher and student (Arslan, 2020). In addition, not every student is disciplined; therefore, they might not watch the video at home, causing them to fall behind. Finally, implementing the flipped classroom also causes an extra workload on teachers.
In conclusion, the researchers examined the results of each study, and the findings showed the flipped classroom had a positive effect on EFL learners' writing, reading, listening, grammar skills, and achievements in general. Learners had a higher level of motivation, and they were better in writing after implementing the flipped classroom. Learners had higher self-esteem because they could prepare for the lesson before class, which allowed them to express themselves better. Group discussion activities and collaborative learning allowed them to interact, resulting in better communication. EFL teachers had a positive attitude toward using the flipped classroom approach in their classrooms. The most commonly used research method in the analyzed studies was the mixed research method, and the effects of the flipped classroom on EFL learners writing skills were researched more than other topics. This study could guide teacher-researchers who want to use the flipped classroom approach while teaching a second language. It will also help researchers develop ideas on the flipped classroom as a whole. Finally, in the future, more research could be conducted on the effects of the flipped classroom on listening skills of EFL learners in remote online education should be examined as well as the trend of research before and after distance education could also be examined. Making a synthesis of the papers may help guide future research, and it could help researchers determine their research titles and topics.
The research, however, has various limitations. First, analyzed papers in this study were limited to 44 because the researchers could not reach every published research. Therefore, more articles could be analyzed for generalization. Second, the papers were between 2017 and 2021, and not every article in 2021 was analyzed (due to the cut-off date). Third, a content analysis was conducted for this study. Other research methods could be used instead of content analysis. Another limitation of this study is the review scope is not set in a wider range of databases. Therefore, a wider range of databases could be used in future reviews.