## 3 Results and Discussion
### Opportunities That an SBC Project Offers for STEM Education (RQ1)  
The data analysis produced five different categories for opportunities. Three categories--lecture contents (1), planning (2) and supply (3)--addressed the engineering approach and two other categories were about learning (4) and future teaching (5). According to the interviews, the lecture contents should address the possibilities of working examples through already-built devices introduced in the literature., e.g., [23; 25]. The function-and-functionality matrix was found to be helpful for the systematic planning of objectives, components, and budget. However, the component selection should be based on the needs derived from measuring the selected chemical phenomenon, which will determine the necessary functions of the device [31; 32]. This is a crucial aspect to consider in the planning phase, where the concept is evaluated. In addition, the supply phase made it possible to learn new know-how about purchasing components. From the learning and the future teaching perspectives, pre-service chemistry teachers felt that an SBC project offers a good context to implement learning-by-doing through project-based learning. It stimulates the recalling of old knowledge, upon which the new knowledge is built. This offers the possibility to integrate multiple STEM disciplines into the project [35]. In addition, the SBC project was experienced as an important learning opportunity for instrumentation in science, from both the teachers' and the learners' perspectives. This aspect can be used to show the nature of chemistry as an instrumental science. Interview 2 revealed meta-level opportunities. First, managing to build something that works improved the feeling of self-efficacy. Interviewee 2 worked as a substitute teacher during the course, and when she showed the result to her pupils, she felt that she had the opportunity to be a positive role model for life-long learning and support of gender equality in science. The last notion of learning is about the opportunities of the seminar. It enabled peer support, learning from others, and provided some healthy competition with peers. The summary of the observations and the identified solutions for presenting the opportunities are shown, grouped by category, in Table 2.  
\begin{table}
\begin{tabular}{c p{284.5 pt}} \hline \hline
**Category** & **Observations/Solutions** \\ \hline \multirow{3}{*}{\begin{tabular}{c} Lecture \\ contents (1) \\ \end{tabular} } & \begin{tabular}{c} Presentation of opportunities early on, based on working examples. \\ Learn the function-and-functionality matrix for systematic planning of \\ objectives, components, and budget. \\ \end{tabular} \\ \hline \multirow{3}{*}{\begin{tabular}{c} Planning (2) \\ \end{tabular} } & \multirow{3}{*}{Component selection should be based on the needs first} \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \hline \multirow{3}{*}{\
\begin{tabular}{c} Learning (4) \\ \end{tabular} } &
\begin{tabular}{c} Context for project-based learning \\ Show the instrumentation of science to students \\ SBC project produced a working device with multiple educational opportunities. \\ Opportunity of providing a positive example and a role model. \\ Opportunity of emphasizing and affirmation of gender equality. \\ \end{tabular} \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \cline{1-1}  & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Categorized observations associated with the opportunities of SBC for STEM education (RQ1).