# Visuo-Haptic Simulations to Understand the Dependence of Electric Forces on Distance
## 5 Discussion  
From the results of the previous section (Tables 5 and 6), it can be seen that positive average learning gains were obtained in all student sections, considering the initial five questions of the questionnaire. Given the fact that all students in our sample answered correctly questions \(Q1\) and \(Q2\) of the pre-test and post-test, these questions were removed in the subsequent analysis. This result reflects the fact that all students in the sample already knew the concept that charges of the same sign repel each other, while charges of different signs attract themselves. This basic concept was reviewed at the start of the corresponding courses and was also probably studied in high school physics courses, so the visuo-haptic simulator did not have an impact on it. From Table 7, it can be noticed that the absolute average learning gains for the three-question questionnaire improved as compared to the original five-question questionnaire for the entire student sample, but average relative learning gains remained similar. Likewise, from Table 6, it can be seen that remarkable average absolute and relative learning gains were obtained for questions \(Q4\) (line charge) and \(Q5\) (plane charge), but a small learning loss was found for \(Q3\) (point charge). The two-tail \(t\)-tests presented in this table show that the learning loss in \(Q3\) is not statistically significant, \begin{table}
\begin{tabular}{l l} \hline \hline
**Student** & **Statement** \\ \hline Student 1 & It was a very interesting activity using the devices complements the theoretical knowledge. \\ \hline Student 2 & The activity was really very useful and fun and I think that these types of activities should be used more often in science subjects. \\ \hline Student 3 & I really liked it since we managed to get a better idea of the forces on the charges as well as to feel them. \\ \hline Student 4 & It was very useful to observe the dependency between certain factors and electrical forces. It helped me to complement what was theoretically seen. \\ \hline Student 5 & I liked it and it helped me to understand something that theoretically is sometimes very abstract. It helped me to understand the topics seen in class. \\ \hline Student 6 & It is very educational and fun. \\ \hline Student 7 & Good; however, the instructions could be clearer but the overall experience was excellent. \\ \hline Student 8 & Very good practice, just need to improve the instructions for the activity to deliver. \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Excerpt of students comments at the end of the haptic session. Figure 15: Percentage distribution of the students that recommend to use the visuo-haptic simulators to \((a)\) other Electricity and Magnetism themes (green) or \((b)\) other Physics courses (blue). while the learning gains for \(Q4\) and \(Q5\) are. In particular, it is interesting to observe that almost all students in the sample answered correctly question \(Q5\). These results suggest that the experiment involving visuo-haptic simulators helped students to understand the distance dependence of electrical forces for the line charge and for the plane charge, but had a neutral impact on the point charge case. This can be explained by the fact that most engineering students in our sample were already familiar with the \(1/r^{2}\) dependence on distance for the electric force between point charges, because this concept is addressed at the start of all typical electricity courses, so the visuo-haptic simulator is not expected to have a significant impact on it. The results of this study suggest that the impact on student learning of the visuo-haptic simulators was larger for the EM students than for EF ones. In fact, while EM students obtained statistically significant learning gains for questions \(Q4\) and \(Q5\), EF students only achieved it for \(Q5\).