Introduction

Given the ubiquity of online courses and programs in higher education, it is easy to forget that both the research and practice of online education is still in its infancy. A mere three decades ago, John Verduin and Thomas Clark, could offer this observation regarding the current state of distance education in the United States:

Distance education, although a popular and effective concept in other countries, is still something of an unknown quantity in the United States and, with the possible exception of correspondence courses and telecourses, has until now had little impact here.

(Verduin & Clark, 1991, p. 9)

While this may have been an accurate portrayal of U.S. distance education in the early 1990s, things look significantly different in the 2020s. Before the disruptions of the 2020 COVID-19 pandemic, it was estimated that nearly all public colleges and universities (96–97%) offered online courses and that more than 1/3 of post-secondary students in the U.S. were enrolled in at least one online course (National Center for Education Statistics, 2019, 2021; Seaman et al., 2018). By fall 2021, enrollments in online courses had risen to 61% for undergraduates and 56% for graduates (National Center for Education Statistics, 2023).

The rise in online courses, programs, and enrollments has been accompanied by a proliferation of literature and research into online education. At the commencement of the new millennium, there were a handful of online learning conferences and just a few scholarly journals publishing studies of online learning and instruction. For example, in the U.S., the Online Learning Consortium, formerly Sloan Consortium, hosts conferences and has supported peer-reviewed research journals such as Online Learning Journal launched in 1996 (Online Learning Consortium, 2023) and MERLOT Journal of Online Learning and Teaching (JOLT) first published online in 2005 (MERLOT, 2023). Currently, Contact North/Contact Nord, a non-profit education group supported by the Canadian government, publishes a “Directory of Selected Journals in Online and Distance Learning” with links to 172 different journals at https://teachonline.ca/tools-trends/journals. It also provides a list of more than 2,000 educational technology/online learning conferences at https://teachonline.ca/training-opportunities/upcoming-conferences. Another indicator of the rise in prominence of online learning research is that the American Education Research Association—the nation’s preeminent conference for education research—has seen a nearly 50% increase in the number of papers addressing online topics during the past three years (Marcus, 2022).

Achievement and Outcomes

Although the quantity of research into online education has increased, Barbara Lockee and her colleagues (1999, 2001), lamented that much of the early studies had a heavy focus on comparisons of outcomes of online instruction with traditional (i.e., in-person, classroom-based) instruction. Such media comparison research has long been denounced by many scholars as being inadequate to explain effects on learning. Criticisms include the lack of control for extraneous variables (Clark, 1994; Lockee, 2001); weak methodology (Means et al., 2014; Phipps & Merisotis, 1999), assuming that each media has fixed attributes that work the same with all learners (Clark, 1994), and being based on local practice, rather than theory, limiting its generalizability (Perraton, 2000).

One of the earliest major media comparison studies was performed at the University of Chicago 100 years ago. The researchers investigated the educational use of motion pictures compared to slides, stereographics, still pictures, and “conventional” (i.e., non-mediated classroom-based) instruction during more than three years at eight public school systems (Freeman, 1924). The results found that: (1) no medium was superior to the other; (2) learning was influenced by the characteristics of the learner and the methods of instruction, not by the delivery mechanism; and (3) students can learn from instruction delivered via media. In their review of educational technology research literature, Thompson and her colleagues (1996) stated that the Freeman study should have marked the end of media comparison studies since subsequent studies for the remainder of the 20th century largely reinforced the findings of the Freeman study.

The most notable effort to overcome the methodological limitations of the vast majority of media comparison studies was undertaken by Barbara Means and her colleagues in their meta-analysis conducted for the U.S. Department of Education (Means et al., 2009, 2014).

In contrast to many previous meta-analyses, we excluded studies of computer-based or distance learning that did not use the Internet and we confined our analysis to measures of student learning and did not consider effects on students’ perception of how well they learned or their liking for the online experience.

(Means et al., 2014, p. 20)

They included only studies that measured learning outcomes for control and treatment groups, used a rigorous quantitative analysis, and provided sufficient information to calculate effect sizes. Of 1,132 possible studies, 99 met these criteria.

In keeping with prior analyses, they found no significant difference in learning outcomes between online and in-person instruction. They did find significant positive differences in achievement in learners in blended/hybrid courses over both in-person and fully online. However, as indicated by Clark (1994), these advantages were due to the pedagogical approaches used to capitalize on the affordances provided by the blend of the online and in-person environment—not merely the delivery system itself. Some of these approaches included high levels of online engagement and interactivity by the instructor, opportunities for learner collaborations online and in class, and the ability for the learners to take advantage of visual media and instructional content in the learning management system and repeat it as often as needed (Means et al., 2014).

One area in which studies have been consistent and worrisome for advocates of online learning is the difference in the persistence of online versus on-campus learners. Studies have shown higher rates of attrition among online learners (Angelino et al., 2007; Shaw et al., 2016; Xu & Jaggers, 2013). Some have taken this to mean that online learning is an ill-fit for first-year students, low-income students, and students of color. However, as with media comparison studies, focusing on the online course as the sole independent variable can ignore the significant role that institutional factors that occur independent of the online course—such as the lack of equivalent student services and resources between on-campus and online students—have on online student retention. Attrition can be greatly influenced by what does or does not occur outside of the online course (Braddock et al., 2018; Travers, 2016).

Research Topics

While online learner achievement and retention are two obvious topics of high interest for researchers, not all online education topics have received equitable or adequate coverage in the research literature. Florence Martin and her colleagues (2019) analyzed research topics from meta-analyses of more than 2,000 studies published between 1990 and 2018:

1. –890 journal articles and dissertation abstracts from 1990–1999 (Berge & Mrozowski, 2001).
2. –695 articles between 2000–2008 (Zawacki-Richter et al., 2009).
3. –619 articles between 2009–2018 (Martin et al., 2019).

Three categories yielded the greatest number of studies: online learner characteristics, course design, and strategies to increase engagement, active learning, and learning communities.

Consistent across nearly three decades of published studies is a lack of research into administrative, management, and organizational issues in online learning. While there is a robust literature for online teachers and instructional designers, there is a dearth of literature to guide organizational leaders who must make critical decisions regarding how online education is staffed, funded, and administered at their institutions (Huett & Piña, 2016). A chapter on research in online administration and management was planned by two of the editors of this Handbook but was abandoned due to the paucity of empirical-based studies in this area.

The Handbook of Research in Online Learning

As a nascent and evolving discipline and field of study, the research base of online learning, instruction, design, and administration lags far behind their actual practice at educational institutions. The studies included in this Handbook include many of the most salient topics in online education. The included chapters bring together diverse perspectives that collectively span the current landscape and will help shape future global online education. The book is divided into four major categories: (1) Reviews, Models, and Frameworks for Online Learning; (2) Insights about Learners and Learning Engagement; (3) Teaching and Instructional Support in Online Environment; and (4) Advances and Applications in Online Learning. Readers will be edified and enlightened by chapters describing the current knowledge base of online education, including research design and analysis; theories, models, and frameworks; instructional design; learner and instructor engagement and interaction; learning technologies; learning environments; learning communities; faculty development and support; learner development and support; evaluation and quality assurance; online teaching strategies; soft skills; open educational resources; gamification; and artificial intelligence. The Editors of the Handbook of Research in Online Learning express deep appreciation and gratitude for the contributions of 65 of the most active and talented researchers in the field of educational technology and distance learning. Their work enriches our understanding and inspires transformations.