## 2 Materials and Methods
### Description of the Instruments  
The survey was complex, and several scales were used as instruments. The items that made up each scale and the results of the statistical analyses are presented in the form of tables in the Results section. The instruments were as follows:  
1. Frequency analysis of responses to the question about ownership of ICT devices. We asked students about ownership of smartphones, tablets, and personal computers. The response format was yes or no. The results are shown in Table 1.  
2. Frequency analysis of the use of a smartphone and/or tablet computer (tablets) during the last school year in the lessons of the following compulsory subjects in 8 th and 9 th grade. We asked students, \"During the last school year, how often did you use a smartphone and/or tablet computer (tablets) in class in the following 8 th and 9 th grade school subjects?\" A list of ten compulsory subjects was offered. The response format was a 6-point scale with the options (1) never; (2) very rarely; (3) rarely; (4) often; (5) frequently; and (6) very frequently. The results of the statistical analysis are presented in Table 2.  
3. Frequency analysis of responses to the question about first-time use of smartphones for educational purposes. Students were presented with a set of four numbers related to the grade levels of 9-year Slovenian compulsory school with instructions to circle the appropriate number. Slovenian elementary school is divided into three thirds (cycles). The first two three-year cycles can be recognized as primary grades (ISCED 1) and, with the exception of the sixth grade, are mostly taught by primary teachers who teach all subjects. The last three-year cycle is taught by subject teachers and can be classified as lower secondary (ISCED 2). The fourth number was labeled \"never.\" The items and results are presented in Table 3. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Item** & **YES** & **NO** \\ \hline I own a smartphone & 303 (97.1\%) & 9 (2.9\%) \\ \hline I own a tablet & 135 (43.3\%) & 177 (56.7\%) \\ \hline I own a computer & 247 (79.2\%) & 65 (20.8\%) \\ \hline I have to share my smartphone with siblings. & 24 (7.7\%) & 288 (92.3\%) \\ \hline I have to share my tablet with siblings. & 87 (27.9\%) & 225 (72.1\%) \\ \hline I have to share my computer with siblings. & 114 (36.5\%) & 198 (63.5\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Frequency analysis of the ownership of ICT (N = 312). \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline
**Subject** & **1** & **2** & **3** & **4** & **5** & **6** & **Median** & **Mode** \\ \hline Foreign language & 26.8 & 8.0 & 14.7 & 19.8 & 15.3 & 15.3 & 4 & 1 \\ Biology & 21.7 & 17.6 & 16.6 & 20.8 & 14.7 & 8.6 & 3 & 1 \\ Chemistry & 27.5 & 17.9 & 15.7 & 21.4 & 11.5 & 6.1 & 3 & 1 \\ Geography & 31.9 & 11.5 & 14.4 & 19.8 & 12.1 & 10.2 & 3 & 1 \\ Physics & 38.8 & 13.1 & 15.7 & 16.3 & 9.6 & 6.4 & 2 & 1 \\ Slovenian & 41.9 & 11.5 & 9.6 & 16.9 & 10.2 & 9.9 & 2 & 1 \\ Mathematics & 42.1 & 12.9 & 10.6 & 15.1 & 7.7 & 11.6 & 2 & 1 \\ History & 44.1 & 13.4 & 10.2 & 13.7 & 7.7 & 10.9 & 2 & 1 \\ Arts & 49.5 & 13.1 & 9.3 & 13.1 & 8.3 & 6.7 & 2 & 1 \\ Sport & 63.9 & 13.4 & 6.7 & 6.7 & 4.5 & 4.8 & 1 & 1 \\ \hline \hline \end{tabular} Note: 1 = never; 2 = very rarely; 3 = rarely; 4 = often; 5 = frequently; 6 = very frequently.  
\end{table} 
Table 2: Frequency analysis of using a smartphone and/or tablet computer (table) during the last school year in class for the following 8 th- and 9 th-grade school subjects (N = 313, McDonald’s omega = 0.902). Results are presented as percentages and sorted by decreasing medians. 4. Satisfaction (SAT) with smartphone use in education. Satisfaction with smartphone use in education was assessed using the modified 5-item instrument based on flow theory [40] and was applied in slightly different versions and contexts than in the studies by [41; 42; 43; 44]. Satisfaction with a device or service can be considered a key factor in continued or discontinued use of a technology or service [45].