Flipping the Technical and Vocational Classroom for Increased Instructional Outcomes

Higher learning institutions are under immense pressure to evolve within the realms of the fourth industrial revolution. Training institutions are anticipated to minimize learning costs in the face of increasing enrolments. The flipped classroom model is a suitable instructional pedagogy to achieve institutional goals considering the current ubiquitousness of information and communication technology. The systematic review was aimed at summarizing and identifying research gaps that help inform future research trajectories. The 3-step review process was composed of articles searching and retrieval, filtering and sorting, and final inclusion. Identified empirical articles were; i.) Retrieved and summarized on the basis of tittles, abstracts, methods and basic findings, ii.) Filtered and sorted on the basis of study discipline, and iii.) Synthesized on the basis of basic findings. It was found that the flipped classroom improved academic performance to a limited extent. Most articles unanimously concurred that the flipped classroom model makes learning enjoyable and enables the development of lower order cognitive skills outside class and higher order cognitive skills through F2F (face to face) active learning. The success of the model in higher education is hinged on excellent planning, implementation and evaluation. Article history: Received: 07 October 2019 Received in revised form: 10 December 2019 Accepted: 20 January 2020 Available online: 29 February 2020


Flipped classroom instructional model was pioneered by Jonathan Bergmann and Aaron
Sams in 2007 (Bergmann & Sams, 2012). The model was initially developed as a means to save time and ensure that absent students catch up after accessing prerecorded instructional materials.
The flipped/ inverted classroom concept is also partially credited to Salman Khan who founded the Khan Academy, a free online system that covers multitudes of topics and subjects (Roach, 2014).
The convectional teacher-centered methods of learning are fast being substituted because of some limitations among them the promotion of rote memorization at the expense of attaining higher order cognitive skills (Kurbanoĝlu & Akkoyunlu, 2016). The obsoleteness of the convectional lecture transmissive model is paving way for the flipped classroom model packaged with active in-class

Innovation of Vocational Technology Education
Available online at http://ejournal.upi.edu/index.php/invotec Higher learning institutions are under immense pressure to evolve within the realms of the fourth industrial revolution. Training institutions are anticipated to minimize learning costs in the face of increasing enrolments. The flipped classroom model is a suitable instructional pedagogy to achieve institutional goals considering the current ubiquitousness of information and communication technology. The systematic review was aimed at summarizing and identifying research gaps that help inform future research trajectories. The 3-step review process was composed of articles searching and retrieval, filtering and sorting, and final inclusion. Identified empirical articles were; i.) Retrieved and summarized on the basis of tittles, abstracts, methods and basic findings, ii.) Filtered and sorted on the basis of study discipline, and iii.) Synthesized on the basis of basic findings. It was found that the flipped classroom improved academic performance to a limited extent. Most articles unanimously concurred that the flipped classroom model makes learning enjoyable and enables the development of lower order cognitive skills outside class and higher order cognitive skills through F2F (face to face) active learning. The success of the model in higher education is hinged on excellent planning, implementation and evaluation. tasks and pre-/post-class work (Abeysekera & Dawson, 2015). Flipped classroom switches the activities traditionally done in class with those used to be completed outside class (Baytiyeh & Naja, 2017;Becker & Birdi, 2018;Blau & Shamir-Inbal, 2017;Calimeris & Sauer, 2015;Engel, Heinz, & Sonntag, 2017;Hao, 2016;Kim et al., 2014;Kong & Song, 2015;Lee & Lai, 2017;Murphy, Chang, & Suaray, 2016;Olitsky & Cosgrove, 2016;Ravishankar, Epps, & Ambikairajah, 2018;Şengel, 2016;Sohrabi & Iraj, 2016;Yilmaz, 2017). In this instructional pedagogy, the teacher acts as a guide or facilitator (Lopes & Soares, 2018). Flipped classroom is sometimes known as the inverted classroom or peer instruction. In a flipped classroom, subject materials are learnt in the form of videos, podcasts, online tutorials, voice over PowerPoint slides or audiovisuals in advance of class attendance (Gulley & Jackson, 2016). The class time is reserved for active learning which enables learners to attain higher-order cognitive skills of the Bloom's taxonomy. In a flipped learning set up, videos, audiovisuals or podcasts are issued in advance of class attendance (Lee & Lai, 2017).
Content is usually accessed outside the classroom through various e-platforms.
A flipped classroom frees up more time for active learning through the use of games (team based learning), experiments, polling software and multimedia resources (Becker & Birdi, 2018).
Video technology is appealing to learners especially outside the classroom. The flipped classroom model supports diversity in students' learning pace, it is time effective, provides point-of-need assistance, provides more active learning opportunities for students, promotes development of higher-order cognitive skills, promotes better student-instructor (one-on-one) interaction, increases student responsibility for learning, addresses multiple learning styles, provides improvement on lecture material, promotes better student engagement and confidence through student-centered learning and collaboration, and provides easy access to the lesson content (Kurbanoĝlu & Akkoyunlu, 2016). Past flipped classroom studies showed that flipped students performs better, are motivated and more satisfied than traditional classroom students (Lee & Lai, 2017;Olitsky & Cosgrove, 2016).
However, the substitution of content delivery mechanism, that is, from traditional lecture-based model to the flipped classroom model might come with adverse learning outcomes if not properly designed and implemented (Kurbanoĝlu & Akkoyunlu, 2016). If students do not view the videos before attending class, active learning might not be enjoyable and lively (Lee & Lai, 2017). Flipped classroom pedagogy add more responsibilities to instructors in terms of making the videos, online quizzes, assignments and other instructional materials (Baytiyeh & Naja, 2017). Students used to having the conventional lecture method may also resist flipped classroom model and might face challenges in acquiring e-devices compatible with high speed internet (Kurbanoĝlu & Akkoyunlu, 2016).
The broad aim of this systematic review was to establish the best evidence on how flipped instructional pedagogy has been applied in TVET-related higher education study disciplines. This article intends to help educators to understand why the adoption of a flipped classroom is inevitable during the current fourth industrial revolution. Educators might also appreciate why learners perceive the flipped classroom model as the instructional model of the moment as advocated by so many authors. The article also seeks to explore the gaps left by flipped classroom studies in measuring its impact on student achievement. Most articles on flipped classroom model dwelt much on the importance of the model on the basis of students' perceptions and little has been raised on how the flipped classroom improve student achievement. The review is also intended to provide a summary and a critique of various flipped classroom research topics and methods. The data could be used to identify important issues and questions in the literature and help to shape future research trajectories of the flipped classroom model.
The rest of the article will focus on the following; a critique of the flipped classroom model (background of flipped classroom), methods, results and discussion as well as the conclusion.

Student-centered learning
In the last decade, there has been a transition from teacher-centered pedagogies and practices to student-centered learning approaches. Latest instructional approaches put students' needs, interests, backgrounds and preferred learning styles ahead of the interests of education practitioners (Kurbanoĝlu & Akkoyunlu, 2016). Researches have shown that, in order to maximize educational outcomes, learning and teaching should be supported by the now ubiquitous information technology (Ferreri & O'Connor, 2013). Higher education has realized that technology supported pedagogies are indispensable in order to enhance active learning, keep students engaged, satisfy students' needs and wants (Sohrabi & Iraj, 2016). That realization gave birth to the integration of face to face and online learning (blended learning and flipped classroom models) (Roehl, Reddy, & Shannon, 2013).

Flipped classroom model
The flipped classroom was first adopted at higher education level following the K-12 practices (Albert & Beatty, 2014). In higher education, it is mostly applied at postgraduate level and popular online resources bank at the disposal of instructors like Khan Academy, Coursera, and TED talks were developed to promote it (Arnold-Garza, 2014). The flipped classroom is both a skills development and content transmission instructional pedagogy.
The flipped classroom differs with the traditional lecture-based model in that learners are first exposed to learning materials outside class. Students learn the materials in the form of videos, simulations, podcasts, PowerPoint slides to mention a few technology-aided learning materials (Kurbanoĝlu & Akkoyunlu, 2016). In the class, the students apply, synthesize, analyze and evaluate what they would have studied outside class (Olitsky & Cosgrove, 2016). In the classroom the instructor's role will be limited to guidance and the student drives real learning. The purpose of flipping is to ensure that students are engaged in active learning through which they will apply concepts acquired through heutagogy (self-directed learning). In a flipped class, videos are recorded and forwarded to students for watching ahead of class (Kurbanoĝlu & Akkoyunlu, 2016).
In a study about flipped classroom, flipped learning was found to increase grades in the medium-term over the traditional learning (76.6% vs 72.8%). In this study with 3 tests, two out of three revealed that flipped students significantly scored better than students taught face to face, test 1; t (527,295) = -2.666, p<0.008 and test 3; t (558,305) = -2.605, p<0. 009 (Albert & Beatty, 2014).
Most studies revealed convincing evidence of a flipped pedagogy with regards to the affective dimension (Rivera, 2015). Most students reported positively about it (Abeysekera & Dawson, 2015;AlJarrah, Thomas, & Shehab, 2018;Eryilmaz & Cigdemoglu, 2018;Foster & Stagl, 2018). 78% of the tertiary students in a research conducted in Malaysia reported that video watched were clear and easy to understand (Wang, 2017). The collaborative class sessions are usually time effective because students will be ceased with learning by doing through group and peer instruction (Guerrero et al., 2015;O'Flaherty & Phillips, 2015). However instructor and student commitment is required for it to work (Rivera, 2015). Furthermore, critics argues that, educators might resist its adoption on the basis of the need for the teacher to reevaluate teaching and instructional materials. Flipped classroom pedagogy demands more preparation time by both students and the instructor (Davis, 2016;Foster & Stagl, 2018). 87% of surveyed Hong Kong in-service secondary teachers reported that a flipped pedagogy is time ineffective considering that they were currently struggling with the face to face approach (Wang, 2017).

Class and online learning space
It is imperative to note that active learning is taking center stage. In order to obtain desirable outcomes, the classroom environment should be equipped with necessary ingredients needed for peer instruction (Baepler, Walker, & Driessen, 2014). Moveable desks should be put in a classroom installed with learning equipment like white boards, microphones, wireless internet, overhead projectors and speakers. Instructors ought to act like mentors in a group learning space and should give instant feedback as well as clarify misconceptions (Carter, Carter, & Foss, 2018). Online lectures should be naturally shorter than live lectures because of the absence of side tracking and interruptions (Kerr, 2015).

Searching and retrieval procedure
In the period starting from September to October 2018, research articles were searched and

Students' preference and satisfaction
Most students were impressed by the flipped classroom instructional pedagogy (Al-Zahrani, 2015; Ravishankar, Epps, & Ambikairajah, 2018;Roach, 2014), although a limited number of students maintained their passive learning habits (Chen, Wang, & Chen, 2014). In a case study comprising of 34 clinical pharmacy lecturers, 84% of the lecturers appreciated a flipped classroom pedagogy and 88% of the lecturers promised to adopt the model in their future classes (See & Conry, 2014). Several other researchers also confirmed the same basic finding that a flipped class model is satisfying to both students and instructors than the traditional lecture-based model (Cotta et al., 2016;Chen, Wang, & Chen, 2014;McNally et al., 2017;Michinov, Morice, & Ferrières, 2015;Nikolic, Ros, & Hastie, 2018;Saunders, Green, & Cross, 2017;Street et al., 2015;Tan, Brainard, & Larkin, 2015;Wozny, Balser, & Ives, 2018). For instance, in a survey consisting 120 tutees and 7 tutors, the tutees' average ratings were 6.97 ± 1.93 (from 1=unsatisfactory to 10=excellent). Furthermore, in an action research involving 2 lecturers and varying number of students at each and every interval (2 or 3 or 4), flipped students were seen enjoying the active learning component of the flipped classroom model (Pappalepore & Farrell, 2017). In a questionnaire survey by Hao (2016) with 84 undergraduates studying Information Technology and Education (79.1% females and 20.9% males), 60% of the students reported that they preferred the flipped instructional pedagogy than the traditional lecture method.
In most questionnaire surveys, students were seen to prefer a flipped classroom model to the lecture-based model. For example, 92% of group 1 and 100% of group 2 students liked flipped learning (Sohrabi & Iraj, 2016), 95% were satisfied and 37% suggested that they would wish if flipped learning could be extended to all topics (Ravishankar, Epps, & Ambikairajah, 2018), 90% of engineering students endorsed the flipped model (Kakosimos, 2015;Munir et al., 2018). In a phenomenological study with 14 nursing students, kinesthetic learners were seen to be positive about flipped learning (Cramer's V=0.849, P=0.006), visual learners were negative (Cramer's V=0.701, p=0.032) while auditory learners were indifferent (Cramer's V =0.306, p=0.52) (Green & Schlairet, 2017). Some unique students were also found to prefer some elements of the flipped classroom model. A questionnaire survey involving two courses (Professional Skills in Dietetics, n=148 and Community Nutrition, n=48) revealed that 70%, 64% and 70% of the students liked video lectures, active learning and student-teacher interaction respectively (Gilboy, Heinerichs, & Pazzaglia, 2015). However, in Yilmaz (2017) study, satisfaction and motivation was found to be hinged on students' self-directed learning skills, internet self-efficacy, online communication selfefficacy, and computer self-efficacy.
Conversely, in some studies, students' reaction on the flipped classroom model was lukewarm and others felt that it was not ideal for students of certain backgrounds (Sohrabi & Iraj, 2016). For example, in a two group quasi-experimental study with 343 lecture-based students and 334 flipped students, satisfaction levels were modest (flipped classroom; m=3.631, SD=1.538) on a 6 point Likert scale (He et al., 2016). A descriptive and exploratory study involving nursing students studying Public Health Science and Population Health flipped courses (3rd year, n=64 and 2nd year, n=93) showed no significant differences in course evaluation with regards to flipped learning or traditional learning (Liebert et al., 2016).
Additionally, intriguing findings were found in an experimental study involving two mathematics courses in electrical engineering. Both mathematics course I and III had certain topics flipped. For mathematics course I, students' preference was seen decreasing over time, that is, in summer 2012 (51%), winter 2012/13 (41%), summer 2013 (23%) while 67% of course III students preferred flipped learning in 2012 (Braun, Ritter, & Vasko, 2014). Opposing preferences were also noted in some studies. For instance, in a mixed method, crossover repeated measures study, nursing students learnt pharmacology as follows; both section 1 (n=36) and section 2 (n=40) learnt through convectional lecture method for 6 weeks and followed by 6 weeks of exclusive flipped learning by section 1. It was found that students were more satisfied by the traditional classroom approach than the flipped classroom approach (El-Banna, Whitlow, & McNelis, 2017). An example of a student comment is; "I prefer topic experts leading discussions. Too many students bring nothing to the table" (Hanson, 2016). In addition, a small group (10-15%) of flipped students were reported to prefer the traditional lecture-based method following 4 weeks and 6 weeks of being exposed to traditional lecture method and flipped classroom method respectively (Street et al., 2015). Flipped learning did not completely satisfy all learners in some instances. Quite a number of studies have shown flipped students resisting and hesitant when exposed to flipped learning for the first time although some students were seen gradually adjusting to the new learning set up with time (Elliott, 2015).
A limited number of studies concluded that flipped students were significantly better in terms of grades than traditionally taught students (Olitsky & Cosgrove, 2016). In a randomized experimental study, flipped ophthalmology clerkship students (Flipped class: n=48, Traditional class: n=47) had significant high scores in the post-test (ocular trauma questions) (16.91 ± 1.67) than traditionally taught students (14.92 ± 1.01, p=0.01, Effect size=1.44) (Tang et al., 2017). Using a quasi-experimental design, Calimeris (2018) investigated classes taught using convectional lecture method (fall 2012) and classes exposed to a flipped learning pedagogy (fall 2013 and fall 2014).
Students in flipped classes obtained higher grades in the final exam. In a different study the adoption of a flipped classroom model also improved learning grades for both gifted and less gifted students (Lombardini, Lakkala, & Muukkonen, 2018).
Overall, flipped students had higher pass marks in the second (p=0.001) and third (p=0.002) sessions. Rose et al. (2016) investigated the impact of a modified flipped classroom model. Residents studying Emergency medicine were grouped. Group A viewed videos uninterrupted while group B's video watching was interrupted with in between questions, 2-6 times per every 5-15 minutes interval.
In 2015, group B residents who watched videos integrated with questions performed better than group A although the 2014 post-test results were similar. In a case study by Trpkovska and Bexheti (2017), (Traditional Class 2014: n=36, Flipped Class 2015: n=49, Flipped Class 2016: n=22), flipped students' scores were higher than the traditional students' scores, that is, 73% (2014), 90% (2015) and 93% (2016). Conversely, other studies revealed opposing findings. For example, in a comparative study involving Team-Based Learning and flipped learning approaches, faculty referential exam results and students results confirmed Team-Based Learning approach as a better model than the flipped classroom model (Nishigawa et al., 2017). In addition, Taglieri et al. (2017) discovered that in terms of knowledge retention, traditionally taught students were better than the Flipped Team-based students (62.9 ± 19.3 vs 54.9 ± 15.53, p=0.001). Numerous studies also argued in favor of the traditional lecture-based method. For example, in a pro-convectional lecture-based method, it was found that instructor-led discussions increased students' performance more than peer discussions, 22% vs 14% (Zingaro & Porter, 2014).
However, most studies reported an insignificant impact of a flipped classroom pedagogy on students' achievement. Using a quasi-experimental design, Kakosimos (2015) implemented the Indifferences in exam scores were also reported by Braun, Ritter, and Vasko (2014).
Adding on, Cotta et al. (2016) surveyed students studying pharmaceutical calculation course.
The 2011 cohort (n=165) had section 1 exposed to the flipped classroom pedagogy and section 2 exposed to the traditional lecture-based pedagogy. All sections of the 2012 cohort (n=151) exclusively learnt through the flipped classroom model. It was found that the 2012 cohort had better grades in section 2 materials (exam 2, p=0.013) and final exam part B, P=0.001 than 2011 cohort.
That showed that in section 1 materials (exam 1) and final exam part A, no significant differences were realized. Several studies did not present convincing evidence on the impact of flipping the classroom on learners' performance (El-Banna, Whitlow, & McNelis, 2017).

Out-of-class preparations
Numerous articles reported about the fundamental importance of preparing for active learning.
Several researchers discovered that video viewing habits decelerated with the passage of time. For instance, Patanwala, Erstad, and Murphy (2017) found that 74% of the students adequately prepared for session 1, 53% prepared for session 2/ 3 and 36% prepared for session 4. Additionally, Beatty, Merchant, and Albert (2017)  A notable video watching trend was also discovered. Most students watched videos when approaching exams. The study by Gulley and Jackson (2016) involving 81 video and 28 non-video students concluded that students were inclined to watch videos when preparing for exams. In that study, only 50% of the videos were fully watched. Patanwala, Erstad, and Murphy (2017) found that the median video view time was higher when students were required to complete a quiz than when there was no quiz [80 minutes (IQR: 38-114) versus 69 minutes (IQR: 3-105), p < 0.001].
Generally, most e-lectures were accessed, viewed and highly rated by the majority of the students outside class (Engel, Heinz, & Sonntag, 2017;Le Roux & Nagel, 2018). 48% of best students and 34% of low performing students watched videos (Beatty, Merchant, & Albert, 2017). Hanson (2016) found that 88% (n=23) in 2013 and 64% (n=16) in 2014 enjoyed watching and replaying e-lectures. 35% (2013) and 32% (2014) of the students watched 75% of the videos. The accompanying quizzes created a culture of studying e-lectures by students (Sohrabi & Iraj, 2016). However, in Hao (2016) study, 50% of the students registered displeasure with video previews and the completion of quizzes outside class. Unprepared students were also found going through electures in class (AlJarrah, Thomas, & Shehab, 2018). Students cited family, health, life, and work commitments, materials volumes and lack of time as major preparation obstacles (Hanson, 2016;Tan, Brainard, & Larkin, 2015). Not surprisingly, a number of students were concerned with the inability to ask questions following video views (Gilboy, Heinerichs,& Pazzaglia, 2015) and increased workload (Lombardini, Lakkala, & Muukkonen, 2018). Students were also found failing to understand technical language presented in the learning videos (Green & Schlairet, 2017) and struggled to adjust to a flipped classroom model at its launch (Mason, Shuman, and Cook, 2013), although some of the students gradually adjusted. The flipped classroom model has potential to give desirable learning outcomes, if classroom practitioners and students prepare for active learning (Graham et al., 2017). In Long, Cummins, and Waugh (2017) study, instructors who attended the summer teaching institute training discovered the need to incentivize students to prepare and the need to timeously attend students' learning needs as critical. Instructors concurred that there was need to be well organized in terms of instructional goals and design.
A dual case study (Case 1: Flipped part-time students, Case 2: Inverted Academic Seminar) revealed that an inverted classroom environment was conducive for clarity seeking, appealing, encouraged collaboration, increased student engagement, and was ideal for students with heterogeneous learning needs (Engel, Heinz, & Sonntag, 2017). Social anxieties were eliminated within a cooperative flipped group compared to an individual flipped group (Eryilmaz & Cigdemoglu, 2018). Hsu (2018) evaluated peer instruction aided by a smartphone application with two handles, time sequence-mode and like-ranking mode. The time sequence-mode (n=36) was the experiment and the like-ranking mode was the control (n=26). The findings revealed that the like-ranking mode accelerated the interaction between asking and answering questions, decreased quantities of useless messages, and refocused attention to questionable messages.

Learning effort, time and pace
The majority of the articles concurred that the flipped classroom model is time effective and maximizes learning outcomes (Gulley & Jackson, 2016). Peer instruction eliminates the monotonous banking of knowledge experienced in an instructor-centered learning space. Most authors reported that the flipped classroom model allowed students to watch videos at own time, own pace, pause, rewind, fast forward videos as they please (Braun, Ritter, & Vasko, 2014;Pappalepore & Farrell, 2017;Roach, 2014). However flipped students were found to study longer before attending class

Cognitive skills formation
The majority of the articles concurred that a flipped classroom model was instrumental in the development Bloom's lower-order skills outside class and higher-order cognitive skills in the classroom (Hanson, 2016). Generally, most articles acknowledged that the flipped pedagogy enabled students to develop analytic, communication, problem solving, critical thinking, and creativity skills as well as fostering team work and self-regulation (Betihavas et al., 2016;Baytiyeh & Naja, 2017;Morosan, Dawson, & Whalen, 2017;Tang et al., 2017). Most students felt flipped learning was flexible, supportive, enabled heutagogy and active learning which fosters engagement (Simpson & Richards, 2015).

Preparatory behaviors
Students reacted differently to video viewing. Students in some empirical studies enjoyed video viewing. One possible explanation is that video lectures could have been short, interesting, interactive and precise or could have been considered the best alternative. Assuming learning independence could have overjoyed a significant number of learners. Popular reasons cited by literature includes video clarity, chronological presentation of concepts (Zainuddin & Attaran, 2016), short and precise, 10 minutes (Fidalgo-Blanco et al., 2017), 10-20 minutes (Graham et al., 2017), and 5-15 minutes (He, Holton, & Farkas, 2018). A significant correlation existed between video viewing and exam scores (Patanwala, Erstad, & Murphy, 2017). This implies that long and uninteresting videos should be avoided at all costs as they can cause students to disengage with the learning materials. The accompanying quizzes and pending exams pushed students to prepare (Gulley & Jackson, 2016). Although flipped learning fostered self-regulated learning, the use of unfamiliar language can turn off students' preparatory efforts (Green & Schlairet, 2017).
On the contrary, taking lectures outside class in the form e-lectures produced unintended learning outcomes. For instance some students did not prepare before attending class (AlJarrah, Thomas, & Shehab, 2018). In some studies, preparatory work was adversely affected by unplanned eventualities/exogeneous factors. Popular cited exogenous factors included family, life, health, and work commitments (Hanson, 2016;Tan, Brainard, & Larkin, 2015). In some related studies, instructors resisted the flipped model because they considered it too demanding in terms of preparation, needed resources and required specialized IT support (Lee & Lai, 2017).

Stakeholders feelings
Overall, the review revealed overwhelming empirical evidence about how the flipped classroom model satisfies both instructors and students. Video lectures, Face to Face (F2F), and student-instructor interactivity were some of the ingredients that excited learners (Gilboy, Heinerichs, & Pazzaglia, 2015). However, Yilmaz (2017) suggested that students' self-directed learning skills, internet self-efficacy, online communication self-efficacy, and computer self-efficacy were necessary determinants for student satisfaction and motivation in a flipped classroom. This might explain why students preferred the flipped classroom approach. Most students and instructors now possess these skills because of the ubiquitousness of information technology.
On the other hand, when surveyed on how satisfying and whether they prefer a flipped pedagogy, some students were lukewarm in their responses (Sohrabi & Iraj, 2016). They could have shown indifferences because of some personal reasons. It could be that they were comfortable with all instructional pedagogies or just undecided. Additionally, some students who highly rated the flipped pedagogy at its launch subsequently developed a bad taste of it. This was shown by less video views with the progression of time (Braun, Ritter, & Vasko, 2014). The nature of students could have influenced their attitude towards the flipped classroom model. For instance, some students openly resisted the model citing various reasons (Elliott, 2015). The resistance was also reflected by instructors as shown by literature. The major reasons for refusing it was its tendency to demand more preparation time.

Students' interactivity, time effectiveness and cognitive skills formation
Generally, most authors concluded that placing video lectures outside class enabled students to obtain lower-order cognitive skills before attending class (Hanson, 2016). During F2F interactions, students developed higher-order cognitive skills. High classroom participation was a sign that students engaged with the materials outside class. Students are less likely to engage with noninteractive learning materials (O'Flaherty & Phillips, 2015). A number of studies concluded that a flipped pedagogy increases students participation (Morosan, Dawson, & Whalen, 2017;Trpkovska & Bexheti, 2017). Flipped classroom model is time effective in that homework is completed in class through peer instruction. Contrastingly, students were found to spent more time in self-directed learning (He et al., 2016). One possible reason could be increased video replays in an attempt to understand the learning materials.

Performance
No sufficient evidence was found on whether the flipped classroom model increased learning outcomes or not. Overall, most studies found that assessment scores were insignificantly higher in flipped classes than in traditional classes (Baytiyeh & Naja, 2017;Beatty, Merchant, & Albert, 2017;Ravishankar, Epps, & Ambikairajah, 2018). Moreover, no significant changes were found between traditionally taught students and their flipped counterparts (Kakosimos, 2015;Nikolic, Ros, & Hastie, 2018). Conversely, in other studies, traditionally taught students significantly performed better than flipped students (Nishigawa et al., 2017;Taglieri et al., 2017;Zingaro & Porter, 2014). One possible explanation is that flipped students had limited opportunities to ask questions as they interfaced with learning materials outside class.
A limited number of studies concluded that the flipped classroom model significantly improves academic performance (Tang et al., 2017;Lombardini, Lakkala, & Muukkonen, 2018). A lot of factors such as learner caliber, resources quality and flipped classroom organization could have influenced the results.

Fostering students' responsibility for their learning success
Education is decisive for the development of the personality and the participation of the individual in the society. It is an indispensable condition for the ability of a modern and democratic society to face the future. The changes culminate in new demands on future concepts of learning and teaching. According to Wilsdorf, in this context not only the content of learning is important, but also the way it is learnt (Wilsdorf, 1991).
In this context, it becomes clear that the flipped classroom approach allows students to shoulder more responsibility for their own learning success. Thus the flipped classroom links up the over-arching goal of academic education, developing with a self-responsible personality, with the methodical approach in learning and teaching in academic institutions (Smith, 2008).
This conjunction is congruously, as ultimately it is an over-arching goal of academic education to promote the development of a self-responsible personalities. Yet, self-responsibility cannot be taught as such. Rather, it is about creating a framework in the educational process that enables the individual to develop into a self-responsible personality.
From this perspective too, flipped classroom is a valuable approach for the design of academic education processes.

Conclusion
The systematic review has identified few literature gaps. None of the empirical articles focused on real time delivery of instruction via online means like video conferencing. Secondly, no article dwelt on online real time F2F peer instruction. Future research should consider the possibility of taking both active learning and video e-lectures outside the classroom.
A big bang approach might be needed with regards to ensuring that everything needed is in place. Instructors should acquire IT skills needed to make learning materials. Instructor training institutions should also expose trainee instructors to the flipped classroom model during training.
The mindsets of all classroom stakeholders should be prepared before implementing the flipped classroom pedagogy. The curriculum renewal processes should be inclusive. Training institutions should invest in relevant IT technologies that facilitates active and self-regulated learning.
The article was intended to summarize empirical studies focusing on the flipped classroom model and identify research gaps that could inform future research trajectory. Previous empirical studies dwelt much on the impact of the flipped classroom pedagogy on students' opinions, academic performance, interactivity, outside class preparation, and flip budget. In this systematic review, technical and vocational related articles were considered. These included, technology, engineering, business, economics, medicinal and health related articles. The flipped classroom model has great potential of improving learning grades in TVET related disciplines to a considerable extent. The flipped classroom model gives enough active learning space for the development of higher-order cognitive skills. Lower order thinking skills can be achieved through heutagogy outside the classroom. The majority of the articles concurred that a flipped classroom pedagogy was satisfying to both instructors and students although concerns on increased workload were raised. The flipped classroom model is cost effective for huge classes (O'Flaherty & Phillips, 2015). The success of the flipped classroom model is hinged on good planning, implementation and evaluation (Long, Cummins, & Waugh, 2017). Learning material should be properly prepared and tested before being used.