## 5 Results and Discussion  
### Evaluation of Quantitative Method  
To measure the usability of the three AR Geography apps, a System Usability Scale (SUS) was performed. Table 2 presents the SUS scores per user group (teachers, pupils, and computer science students) and per AR app, which are acceptable since they are above 70 [37]. It is worth mentioning that the AR app for the 6 th grade: Earth as a living space for humans obtained the highest SUS scores by teachers (82.50) and computer science students (81.99), while it obtained the least satisfactory scores from the pupils (70.00). A possible explanation for this might be that the \"Continents\" game that was chosen for the experiment, focused more on how to present useful information in an understandable and playful way-features that seem to be important for teachers and computer science students as game developers-rather than the interaction-a design feature that seems to be important for the pupils' engagement. Additionally, the total SUS scores are very satisfactory since all the total scores are above 75. The total SUS score per AR app refers to the SUS score that is calculated from the total sample. For example, in the case of the AR app for the 5 th grade, the total sample consisted of 60 participants, who rated the specific AR app with a total SUS score of 79.04. More specifically, Tables 3-5 present the mean values and standard deviations of the responses that participants rated for each AR Geography app. Regarding the AR app for the 5 th grade (see Table 3), the majority of the participants (pupils, teachers, and university students) would like to use this app frequently and they found the app neither complex nor cumbersome to use. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **5 th Grade AR App:** & **6 th Grade AR App: Earth as a** & **6 th Grade AR App:** \\  & **Greece** & **Living Space for Humans** & **Earth as a Celestial Body** \\ \hline
**Teachers** & 73.75 (SD 12.37) & 82.50 (SD 3.68) & 73.75 (SD 5.30) \\
**Pupils** & 70.50 (SD 15.98) & 70.00 (SD 14.61) & 76.07 (SD 9.69) \\
**Comp. ScienceStudents** & 82.26 (SD 11.47) & 85.87 (SD 12.12) & 77.44 (SD 18.54) \\ \hline
**Total** * & 79.04 (SD 13.57) & 81.99 (SD 14.15) & 76.99 (SD 16.47) \\ \hline \hline \end{tabular}  
* Total refers to the total SUS score when the total sample of each AR app is considered.  
\end{table} 
Table 2: Usability scores. \begin{table}
\begin{tabular}{c l l l} \hline \hline  & & **Pupil** & **Teacher** & **Comp.** \\
**Item** & **English Version of SUS** & **Resposes** & **Resposes** & **Science** \\  & & **Mean (Std)** & **Mean (Std)** & **Mean (Std)** \\ \hline Q1 & I think that I would like to use this system frequently. & 4.07 (1.03) & 4.50 (0.71) & 3.95 (0.87) \\ Q2 & I found the system unnecessarily complex. & 2.00 (0.93) & 2.50 (0.71) & 1.44 (0.55) \\ Q3 & I thought that the system was easy to use. & 4.00 (1.00) & 4.00 (0.00) & 4.23 (0.75) \\ Q4 & I think that I would need the support of a technical person to be able to use this system. & 2.40 (1.24) & 3.50 (0.71) & 1.65 (1.04) \\ Q5 & I found that the various functions in this system were well & 4.27 (0.88) & 4.50 (0.71) & 4.14 (0.71) \\ Q6 & I thought that there was too much inconsistency in this system. & 2.40 (1.06) & 2.50 (2.12) & 1.77 (0.95) \\ Q7 & I would imagine that most people would learn to use this system very quickly. & 3.73 (0.96) & 4.50 (0.71) & 4.51 (0.51) \\ Q8 & I found the system very cumbersome to use. & 2.13 (1.41) & 1.50 (0.71) & 1.46 (0.80) \\ Q9 & I felt very confident using the system. & 3.60 (0.99) & 4.00 (0.00) & 4.05 (0.87) \\ Q10 & I needed to learn a lot of things before I could get going with this system. & 2.53 (1.25) & 2.00 (0.00) & 1.65 (0.78) \\ \hline \hline \end{tabular}  
\end{table} 
Table 3: Mean values and standard deviations of participants’ responses for the AR app for 5 th grade: Greece.