Online distance education has a long history associated with the movement and philosophy of Open Education. The Open Education movement led to the creation of Open Universities worldwide, mainly after the 1960s. Later, Computer Science advancements and the Internet enabled the emergence of Open Courseware, Open Educational Resources and Open Educational Practices. More recently, it triggered the explosion of Massive Open Online Courses (MOOCs). MOOCs are openly accessible online courses that are attended by hundreds or thousands of people. Most of the time, they have a duration of a few weeks and are free of charge.

Online learning is becoming increasingly mainstream especially in higher and adult, continuous education. The COVID-19 pandemic accelerated this trend by disrupting attendance-based activities in all levels of education. Remote emergency teaching was enforced worldwide due to health-related physical distancing measures. Ever since its conception, online education mainly relies on two main system types: Asynchronous and synchronous e-learning. Both types depend on software or web applications in two-dimensional digital environments, spanning in-plane digital windows with width and height but without any depth. Standard asynchronous online learning tools include learning management systems (e.g., Moodle, Blackboard), and sometimes also collaborative web applications and social networks. Asynchronous tools serve the flexible, in other words, anytime, anywhere communication and interaction among educators, students and content. Synchronous e-learning systems enable the online meeting of educators and students at the same time in a digital, virtual space. Synchronous online learning is implemented through web conferencing platforms (e.g., Zoom, WebEx, Microsoft Teams, Adobe Connect, Skype).

However, applications operating in 2D, web-based environments have well-documented limitations and inefficiencies. The daily extended use of synchronous online platforms leads to phenomena such as Zoom fatigue. Asynchronous platforms are often plagued by emotional isolation, a detrimental emotion for participation motivation. Consequently, e-learning courses in the above-mentioned platforms face high drop-out rates. This phenomenon reaches its extreme in MOOCs where typical completion rates have been fluctuating around or below 10%. The use of social media and collaborative applications (e.g., blogs, wikis) can improve active engagement but not necessarily address natural communication and users’ emotional stress. 2D platforms have the following limitations that impact education negatively:

• Low self-perception: Users experience a very limited perception of the self in 2D environments. They are represented as disembodied entities through a photo or a live webcam head shot feed with no personalization options.
• No presence: Web conferencing sessions are perceived as video calls to join rather than virtual collective meeting places. Participants in long meetings tend to lean out and be distracted.
• Inactivity: 2D platforms offer limited ways of interaction among participants. Unless instructors initiate a learning activity, students are confined to passive participation with few opportunities to act.
• Crude emotional expression: Users have very limited options to express their feelings through smileys and emojis.

All these limitations can be addressed with 3D, immersive spatial environments.