###### Abstract
Among the challenges of using VRLEs in the classroom include the fact that they: (i) can affect the personal student communication and interpersonal connections in a traditional class if a pedagogical implementation is not carefully designed; (ii) can exhibit lack of flexibility compared to a typical classroom experience where a student can ask questions and receive answers and clarifications (this issue can be addressed by designing more complete pedagogical materials with protocols from instructors); and (iii) can be costly as with other advanced technologies, however rapidly changing markets offer more affordable tools, thus VR will increasingly be used in learning, training, and fostering collaborative projects. The latest advances in the field of VR are related to the users' immersion in the virtual environment [26; 27; 28; 29], which is known as immersive virtual reality (IVR). However, such technology has not yet reached higher education and only a few isolated examples exist to date. There are varied applications based on IVR that can create and explore fullerenes molecules [30], investigate the case study of pneumatics [31], and observe fully programmed robotic manipulators [32], to name but a few. IVR makes use of head-mounted display (HMD) technology, with newer projects that include the CAVE (cave automatic virtual environment) system [33; 34]. [PERSON] et al. [35] have reported a recent application to improve student understanding of complex spatial arrangements using VR. Furthermore, there is an increasing growth in applications based on augmented reality (AR). For instance, [PERSON] et al. [36] have recently described how to improve the learning in civil engineering by focusing on building construction. Besides, there are contemporary studies comparing the effectiveness in learning when using VR, IVR, and traditional methods. Indeed, more recent studies [37] have confirmed that when students use VR in a learning setting, they are more engaged and are more motivated compared to when they use conventional tools such as slide presentations via PowerPoint. In contrast, some investigators [38] have found little or no difference in the learning effectiveness when comparing non-immersive VR and IVR, whereas the learning is reported effective in both cases. Meaningful learning refers to the idea that a learned knowledge (or fact) is fully understood by an individual who can then use it to make connections with other previously known knowledge. Based on the authors' experiences in using technology enhanced learning (TEL), not all VRLEs support the same level of meaningful learning experience and a VRLE may even be attractive to users but not effective at the formative level. Thus, teachers currently face the problem of not knowing what key factors are to be considered when creating or designing their VRLEs in order to achieve a high level of meaningful learning. Furthermore, to the authors' knowledge, there is no publication to date covering the influence of VRLEs' design on meaningful learning. Thus, taking into account the research trajectory of the authors, who have recently designed and implemented several virtual laboratories based on VR and IVR technology in the field of MSE [2; 4; 6; 9; 10; 11; 14; 15; 16; 17; 18; 19; 24; 39; 40; 41], the main objective of this paper is to compare different VRLE designs to elucidate the most suitable features for achieving meaningful learning. Consequently, key factors that a TEL-based VR must have to promote a good level of meaningful learning experience in the classroom are described in this contribution. The implications of the present study are not limited to the field of MSE but are applicable to any other discipline that could readily benefit from using VR or IVR (e.g., biology, chemistry, bioengineering, and medicine).