## 5 Discussion  
The experimental study revealed interesting findings and shed light on the effectiveness of virtual embodied pedagogical agents. The first hypothesis concerns the examination of the agents on students' learning experience and assumes that the agents improve the learning experience of the students. In this regard, the results of the experimental study point out that the overall learning experience of the students is improved when they learn in the virtual environment with the use of pedagogical agents that accompany them during their study. The results of the SUS questionnaires indicate that students have better interaction with the virtual environment and better experience towards the environment's usability when agents were employed as learning companions (72 score for GroupB vs. 79 score for GroupA). Moreover, the results of the Likert-scale questionnaires revealed that agents do improve the learning experience of the students (84.72% for GroupB vs. 81.94% for GroupA), their learning interest (76.39% for GroupB vs. 62.50% for GroupA) as well as their enjoyment (86.11% for GroupB vs. 81.94% for GroupA). The second hypothesis concerns the examination of the embodied pedagogical agents on students' performance and assumes that the agents improve students' performance and comprehension in virtual world educational environments. In this regard, the results of the experimental study reveal that the performance and the knowledge construction of the students are improved with the use of embodied pedagogical agents that accompany them during their study. Specifically, the pre-test, post-test results show that students learned and comprehend better the various concepts when agents are employed and accompany students during their study. The [PERSON]'s test validates the equality of the variances of the two groups. For the pre-test is calculated as F = 8.514, \(p\) = 0.005 and for the post-test F = 14.969, \(p\) = 0.000. The results indicate that there are clear differences in the mean performances of the students from the two groups on the post-test (\(p\) = 0.000 \(<\) 0.05) pointing out that students from GroupB learned better and deeper, reporting improved performance and better knowledge construction. Finally, the third hypothesis concerns the examination of the embodied pedagogical agents on students' cooperation and assumes that the agents enhance students' cooperation and communication with their peers. In this regard, the results of the experimental study reveal that the agents can improve cooperation among the students and can provide means for closer and more efficient cooperation. Moreover, the students' engagement with learning activities is enhanced when agents were employed as learning companions (84.72% for GroupB vs. 80.56% for GroupA).  
The results of the study point out the important role that agents can play in virtual reality educational environments and their great impact on students' learning. The main condition for the efficient integration of agents in virtual reality educational environments concerns the actual involvement of the agents in the learning activities, and the accompany of students by standing near them during the activities. These conditions are substantiated to be highly beneficial for students' learning. The employment of pedagogical agents can have a great impact on students' learning experience and improve their engagement in learning activities, their cooperation with their peers, and most of all, their knowledge construction and performance.