Figure 2 shows the distribution of the TLI-related publications in the periods of 2017–2019 and 2020–2022. These two time spans were chosen to analyze the changes in TLI applications as reported in the publications. There is a marked difference in the total number of publications between the two periods, with only 56 articles identified in the former period and 191 ones in the latter. This result is due to the outbreak of COVID-19, where a significant amount of attention was placed on the development and implementation of TLIs to lessen the impact of the pandemic for teaching and learning.

Figure 3 presents the distribution of the countries/regions of the TLIs from the two periods. The TLIs cover a total of 53 countries/regions. For both periods, the United States had the largest proportion of TLIs, followed by the United Kingdom. Many more countries/regions were covered in the second period (a total of 47) than those in the first period (a total of 23). These results suggest that TLIs in distance learning have received attention in a broader range of countries/regions.

Figure 4 shows the distribution of education levels involved in the TLIs. Most TLIs belong to the undergraduate level in both periods. There is a greater difference in the proportion of TLIs between the undergraduate and postgraduate levels for the second period when compared with the first one–above 80% of the TLIs for the second period belong to the undergraduate level.

A total of 30 subject disciplines were found in the TLI-related publications, as listed in Table 1. This result reveals that the development and implementation of TLIs have been widely emphasized in distance education across various subject disciplines. Figure 5 illustrates the distribution of the top five most frequently addressed subject disciplines. Medicine and nursing is the most frequently addressed subject discipline in the first period, but its proportion dropped significantly in the second period. A majority of TLIs in the second period focused on chemistry, suggesting that this subject discipline has attracted particular attention to innovate its teaching and learning practices.

Educational technologies are the most common types of TLIs identified from the publications. Table 2 shows the types of educational technologies involved in the relevant TLIs.

Figure 7 shows the distribution of the top five types of most commonly used educational technologies in TLIs across the two periods. For the first period, video and audio materials, virtual and augmented reality, and learning management systems were used relevantly more frequently. For the second period, laboratory-based software and hardware became the largest proportion, and video-conferencing tools were also used relatively more frequently. These results indicate a pedagogical change in the use of educational technologies between the two periods, which would be driven by the influences of the pandemic on the mode of lesson delivery and interaction that conventional types of laboratory-based activities which are conducted physically in laboratories needed to be changed.

There are 10 types of teaching and learning approaches and six types of teaching and learning activities identified from the TLIs, as shown in Table 3. Blended, hybrid, and flipped learning approaches were categorized into the same type based on the classification of Tonbuloğlu and Tonbuloğlu (2023). Figure 8 reports the distribution of the teaching and learning approaches across the two periods. Overall, the top three are the blended/hybrid/flipped learning approach, gamification approach, and collaborative learning approach. Comparing the two periods, there have been new approaches which existed in the second period, including the task/project-based approach, visual approach, e-service learning approach, questioning technique, and group formative technique. Furthermore, the accelerated learning approach, which contributed 10% of TLIs in the first period, did not exist in the second period.

Figure 9 shows the distribution of the teaching and learning activities in the TLIs across the two periods. For the second period, laboratory-based activities contributed a majority of TLIs (67%), followed by discussion-based (15%), and writing-based ones (7%). This result suggests a marked instructional change in the use of laboratory-based activities, and aligns with the relatively large proportion of TLIs involving the use of laboratory-based software and hardware in the field of natural sciences (e.g., chemistry) as illustrated above where experiments are common.

There are six types of teaching and learning programs identified in the TLIs (Table 4). Figure 10 shows the distribution of them across the two periods. On-the-job related programs and academic support-related programs were the most frequent overall. For the second period, there was a greater proportion of language-related programs and new types of programs related to specifically laboratory work and medical and healthcare training in a distance learning mode. Also, cross-institution-related programs contributed 30% of TLIs in the first period, but 0% in the second period.

A total of 11 assessment approaches and activities were identified in the TLIs, as shown in Table 5. Their frequency is relatively small, i.e., covering only a total of 14 TLIs. They could be categorized into the summative and formative types in general. E-portfolio, quiz, and writing assignment were found in both periods (N = 1 for each period), and the others occurred once only in the first or second period. Technologies were involved in the assessment activities, such as the use of 3D virtual technology for a tooth identification test, and personalized screencasts for a writing assignment.

Online laboratory-based innovations such as software and hardware, activities, and programs were found to be most common in the TLIs. This also reveals the prominent pedagogical pattern in distance learning of science through online laboratories. Conducting experiments in laboratories is an essential part of the learning experience in science disciplines such as chemistry, engineering, and physics (Sharpe and Abrahams, 2019). They allow students to apply the knowledge they have learnt to develop important experimental skills. However, there are circumstances in which doing experiments in a physical laboratory is not possible or feasible, such as when students are unable to access a laboratory or when they need to perform high-risk experiments that may endanger their lives (Weicht et al., 2012). In these cases, using an online laboratory is a viable alternative.

An online laboratory may exist in the form of a totally online environment in which students create and conduct virtual experiments over the Internet via a computer program in either the classroom or at home (Hlescu et al., 2020), or a remote environment where students conduct real experiments in a physical laboratory by remote access over the Internet (Orduña et al., 2018). Both forms aim to help students experience the process of carrying out experiments and obtaining experimental results. Examples of relevant TLIs include a virtual sampling activity to help chemistry students understand the concept of sampling through a guided learning exercise on the effects of sample size and the number of replicate samples on sampling errors (Dickson-Karn and Orosz, 2021), and an instructional tool called ROXI (Research Opportunity through eXperimental Instruction) to assist chemistry students to run experimental analysis using low-cost data through electronic sensors and command and control software (Larriba et al., 2021).

Another pedagogical pattern pertains to learning through advanced digital technologies, as shown in the findings about the common use of virtual and augmented reality. Virtual reality refers to “a computer-generated 3-D experience in which a user can navigate around, interact with, and be immersed in another world in real time, or at the speed of life” (Briggs, 2002, p.35), whereas augmented reality “combines two dimensional or three-dimensional virtual objects into the real-world environment in real time” (Bhatti et al., 2020, p.3).

As pointed out by Kukulska-Hulme et al. (2021), virtual and augmented reality technologies allow teachers to provide students with exciting learning experiences that include: remote participation (e.g., for field trips to places which would be difficult, dangerous, or impossible to visit for students such as the inside of a volcano), remote presence (e.g., people who cannot be in the physical world are able to interact and work together in a virtual reality environment, manipulating virtual objects and moving around the setting together), simultaneous engagement with the physical world (e.g., learners are able to interact with both the real world and augmented reality elements simultaneously), and a time machine (e.g., students can go on trips through time and engage with historic events or watch landscapes change over the centuries).

Examples of relevant TLIs include the use of virtual reality to assist geo-education students in studying the geography of tourist destinations (Shakirova et al., 2020), and augmented reality to train students in using instructional software authoring tools (Eldokhny and Drwish, 2021).

The pedagogical pattern on blended/hybrid/flipped learning is shown in the findings about the high occurrence of the blended/hybrid/flipped learning approach used in relevant studies in recent years to solve pedagogical problems and enhance student learning. Tonbuloğlu and Tonbuloğlu (2023) classifies blended, hybrid, and flipped learning into the same category with a common feature to combine the presentation environments and teaching methods in various modes. This approach is common in distance education, which emphasizes expanding and maximizing student learning outside the classroom by making best use of the benefits of online and face-to-face teaching (Heinerichs et al., 2016).

This pedagogical pattern features both online instruction and face-to-face instruction. The former is conducted on an online platform where only online materials such as videos, textbooks, and software are made available to students, and the latter takes place in a physical classroom where the teacher is present to guide students and provide them with immediate feedback (Nugroho and Wahyono, 2019). Blended/hybrid/flipped learning provides teachers with opportunities to create a flexible environment where the physical space can be used to enable group work. Teachers and students can make best use of their own devices to enhance their teaching and learning.

Examples of relevant TLIs include the use of a flipped learning approach to increase teacher–student interactions in a general chemistry course (Christiansen et al., 2017) and the use of a scaffolded inverse blended learning approach to help students engage with learning activities at higher cognitive levels (Ang, 2020).

Technological advances have facilitated the development of computer-based multimedia materials such as videos and recordings. This not only creates a multimedia-rich environment in which students are able to interact with different audio–visual resources, but also provides students with an active learning experience that has an impact on their engagement (Tugetkin and Dursun, 2022). Computer-based multimedia materials can be either animated or interactive in nature (Kukulska-Hulme et al., 2020; Tugetkin and Dursun, 2022).

Animated multimedia such as animated videos is used to reveal processes that are too fast for learners to follow or too small to see. It also shows the ways in which difficult problems are tackled by an expert, and explain abstract issues in the real world such as an animated weather map showing changes in air pressure. Interactive multimedia such as interactive videos or audio is used to increase students’ motivation and make their learning process more enjoyable.

Examples of relevant TLIs include the use of interactive online videos to promote active learning and help students remain on-task and accountable for their work (Pulukuri and Abrams, 2020), and the application of virtual choir recordings to help students practice duets (e.g., soprano-alto and tenor-bass; Eren and Oztug, 2020).

This pedagogical pattern involves the application of a game and its design elements in a non-gaming context (Khaleel et al., 2015). A game refers to “a rule-based formal system with a variable and quantifiable outcome, where different outcomes are assigned different values, the player exerts effort in order to influence the outcome, the player feels attached to the outcome, and the consequences of the activity are optional and negotiable” (Juul, 2003, p.53).

A gamification approach to teaching and learning can take various forms (Sharples et al., 2013). In its simplest form, teachers may use games that cover ordinary educational tasks and give rewards to students who successfully complete them. Another way is to make use of the trappings of games, such as badges, scores, and timed challenges, to make drill-and-practice work more appealing. A more sophisticated way is to situate learning within a game environment or virtual world.

Instances of relevant TLIs can be seen in the studies of Barbieri et al. (2021), Pakinee and Puritat (2021) and Raharjo et al. (2021), in which the use of a gamification approach was adopted to improve engagement with students and promote active learning and increase student engagement in the class, respectively.

Learning through tasks/projects involves a group of students completing a task or project, thereby achieving a deeper understanding and obtaining different learning outcomes. For it to be effective, the approach must be (1) problem-based, meaning that the project/task should involve a question or problem that drives students to encounter or struggle with the central concepts and principles of a discipline; (2) realistic, meaning that the project/task should involve a question or problem that is relevant and meaningful to students’ own interests and daily lives; (3) student-driven, meaning that the project/task should be student-led, involving more student autonomy, choice, unsupervised work time, and responsibility; and (4) focused on knowledge transformation and construction, meaning that the project/task should involve learning processes which involve inquiry, knowledge building, and resolution such as decision-making, problem-finding, problem-solving, or model-building (Thomas, 2000).

Examples of relevant TLIs can be seen in the research studies of Kato et al. (2020) and Panova et al. (2021), in which a project-based learning approach was implemented to increase student motivation and willingness to communication and to stimulate the development of various types of thinking among students, respectively.

The use of a collaborative learning approach was found to occur commonly in the TLIs. Collaborative learning involves “any of the variety of strategies employed by an instructor to promote students working together to advance their understanding of a subject matter” and these strategies are capable of “prompting students to interact with one another, encouraging them to articulate their perspectives and to resolve differences in understanding” (Osman et al., 2011, p. 547). Collaborative learning also helps to develop a social support system for learners, increase students’ self-esteem, reduce students’ anxiety, promote critical thinking skills, personalize large lectures, and promote active learning (Laal and Ghodsi, 2012).

Instances of relevant TLIs include the research by Raymond et al. (2016) in which a collaborative peer learning approach was implemented in a medical course offered for nursing students in order to foster collaboration among them and prepare them for their future careers, and that of Wenzel (2020) in which a collaborative group learning approach was implemented in analytical chemistry to facilitate the teaching of a large online class.

A wide variety of TLIs that facilitate students to conduct laboratory experiments outside the classroom (e.g., online laboratory programs, activities, software, and hardware) have been implemented in distance learning courses in science subjects such as chemistry and biology. This finding has an implication regarding the use of online laboratories as a substitute for physical ones in distance learning science courses. Conducting laboratory experiments is an integral part of the learning experience in various science disciplines. However, there are circumstances where students are unable to attend physical laboratories; for instance, because of full-time work commitments or experiments being too dangerous. This makes online laboratories a possible and feasible option. Prior studies have consistently revealed the benefits of online laboratories on students’ learning, ranging from enhancing their soft skills (e.g., creativity, problem-solving skills, and critical thinking skills) to their hard skills (e.g., experimental skills and knowledge of science subjects; Destino and Cunningham, 2020; Seaton et al., 2021; Vargas-Oviedo et al., 2021). Management of distance learning institutions should consider the use of online laboratories as an alternative to physical ones, particularly in the post-COVID-19 period, and, if so, the extent to which they could be integrated into laboratory-based distance learning courses.

Virtual and augmented reality, among the technology-based TLIs identified, was found to be the second most frequently used in distance learning. Virtual and augmented reality technologies have been applied in distance learning in various subject disciplines, such as chemistry (Levonis et al., 2021), English language (Urueta and Ogi, 2021), architecture (Kowalski et al., 2020), and geology (Jeffery et al., 2021). Studies focusing on their applications in distance learning have found positive outcomes on teaching and learning, such as promoting active learning (Broyer et al., 2021), improving acquisition of subject knowledge (Kowalski et al., 2020), and enhancing digital literacy (Eldokhny and Drwish, 2021). However, a major drawback of virtual and augmented reality has been its cost and complexity. As such, not all distance learning institutions are able to afford relevant equipment, and not all distance learning teachers are familiar with this type of technology. Thus, management should consider not only allocating funding for the purchase of technologies to promote virtual and augmented reality-based distance learning, but also providing distance learning teachers with professional training on ways to apply virtual and augmented reality to their teaching disciplines.

Pedagogy-based TLIs such as the gamification approach, task/project-based learning approach, and collaborative learning approach have been implemented in distance learning courses in subject disciplines such as nursing (Raymond et al., 2016), Japanese language (Kato et al., 2020), and media communication (Pakinee and Puritat, 2021). This finding offers an implication in relation to pedagogical approaches to distance learning. Distance learning teachers may have a tendency to focus on using pedagogical approaches with which they are familiar, thereby constraining themselves from diversifying their pedagogies. In this regard, management should consider providing incentives such as teaching development grants to encourage teachers to design, implement, and examine pedagogical approaches to distance learning specific to their own disciplines. Doing so would help in not only transforming pedagogy-based innovations into research studies, but also enhancing the quality of teaching for students.

Multimedia is one of the most frequent types of TLIs in distance learning. Distance education has been evolving from relying on hard-copy printed learning materials to audio–visual learning and technology-based learning (Yan and Batako, 2020). This evolution has allowed distance learning teachers to experiment with various educational technologies that best suit their own teaching practices. It has also enriched distance learning students’ learning experiences by providing a wide range of multimedia resources that best facilitate their learning outcomes. The extent to which multimedia resources can be effectively exploited depends largely on the interactivity of the multimedia teaching and learning materials used; that is, the inclusion of different multimedia elements in the teaching and learning materials (Prasetya et al., 2018). In order to optimize multimedia-based distance learning, distance learning teachers must augment interactivity by supplementing their lessons with smart classroom technologies such as interactive whiteboards, interactive mobile devices (e.g., tablets and smartphones), and interactive learning platforms (e.g., learning apps), while at the same time incorporating into the design of instructional materials both interactive elements (e.g., quizzes, multiple choice questions, discussions, and hotspots) and multimodal elements (e.g., images, sounds, videos, and animations). This would not only help the creation of an interactive and fun learning environment, but also to engagement of students’ attention and interest in the lessons (Kusuma et al., 2021).