## 4 Experimental Evaluations
### Methods and Results  
The experimental studies consisted of two different scenarios and examined students learning experience and comprehension. The first scenario involved an instance of the virtual world where students could study along with the pedagogical agents who provided them with different learning activities. After the start of a learning activity, the students were on their own to accomplish each activity. The students could ask for help and assistance, and hint messages were provided via the instant messaging chat area of the interface. The second scenario involved an instance of the virtual world where students could study and complete the learning activities with the full functionality of the embodied pedagogical agents. Specifically, at the start of the learning activities, the embodied pedagogical agent described the context of the activity and accompanied the student. The agent was all the time near the student walking side by side and provided students with the opportunity to interact, so as to get guidance on how to proceed with the activity and assistance related to possible errors made. The content of the system's guidance and assistance was exactly the same in the two scenarios. However, the agent was absent in the first scenario and all the help messages were provided as messages in the chat area of the environment. An experimental/control, pretest/posttest approach was followed in the study. Its phases are illustrated in Figure 5. Initially, the participating students in the study were asked to create their accounts in the AVARES environment. During the registration, personal information such as gender, years of study, and contact information were requested. After that, the students were randomly divided into two size groups that had the same size of 72 students each, and were named GroupA and GroupB respectively. The rates of girls and boys in GroupA were almost the same as GroupB. All the students from both groups participated in and took a pre-test that aimed to assess their prior knowledge before the start of the learning phase in the AVARES environment. The pre-test consisted of multiple-choice questions, and its duration was 25 min. The experiment was conducted in the computer laboratory at the university. After the pre-test, the learning phase took place. The students from GroupA studied in an instance of the AVARES under the first scenario whilst, the students from GroupB in an instance under the second scenario. In order to analyze students' performance, the mean value and the standard deviation were calculated for the pre-test. As shown in Table 1, the mean value and standard deviation were 4.201 and 0.540 for the experimental group (GroupA), and 4.368 and 0.639 for the control group (GroupB), respectively. The results indicate that the students from both groups had the same knowledge level before participation in the learning phase. After that, the learning phase took place and the students from each group were asked to study for a period of five weeks in the scenario of their group. After the end of the five-week phase, a post-test evaluation was performed. Specifically, all the students took a post-test that consisted again \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Group** & **N** & **Mean** & **Standard Deviation** \\ \hline Pre-test & GroupA & 72 & 4.201 & 0.540 \\  & GroupB & 72 & 4.368 & 0.639 \\ Post-test & GroupA & 72 & 6.750 & 0.745 \\  & GroupB & 72 & 8.090 & 0.983 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Statistical analyses of pre-test and post-test results. Figure 5: The main parts of the study. of multiple-choice questions and were of the same difficulty as the ones of the pre-test. The students were given again the same time (25 min) to complete the post-test. The post-test results are illustrated in Table 2, and show that [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.