Pre-service chemistry teachers’ pedagogical content knowledge for integrated STEM development with LESMeR model

Sevgi Aydin-Gunbatar*a, Betul Ekiz-Kirana and Elif Selcan Oztayb
aVan Yuzuncu Yil University, College of Education, Mathematics and Science Education Department, Van, Turkey. E-mail: sevgi.aydin45@hotmail.com
bVan Yuzuncu Yil University, College of Education, Primary Education Department, Van, Turkey

Received 8th March 2020 , Accepted 22nd May 2020

First published on 26th May 2020


This study aimed to examine pre-service teachers’ (PST) personal and declarative pedagogical content knowledge (PCK) for integrated science, technology, engineering, and mathematics (STEM) through a 13 week training course. A new model based on research-based practices was proposed. The model includes Learn, Experience, Study with Mentors, and Reflection on own development and learning, and the acronym LESMeR has been coined as the name for this model. The data were collected through Content Representation (CoRe) as pre- and post-lesson plans, semi-structured interviews conducted after the training, and reflection papers written on a weekly basis. Inductive and deductive data analyses were employed. Results revealed that all participants started the training with a topic-specific PCK (PCK A). None of the participants’ pre-CoRe included essential features of integrated STEM. However, after the training, eight participants were able to balance among STEM disciplines, and integrated at least two STEM disciplines; this was coded as PCK for integrated STEM (PCK C). Five PSTs showed PCK for integrated STEM development to some extent but they were unable to achieve balance among STEM disciplines; this was coded as transitional PCK (PCK B). Results revealed that PCK for integrated STEM development requires considerable time and support. Implications are provided for integrated STEM education.


Introduction

Although the existence of the idea of integrated Science, Technology, Engineering, and Mathematics (STEM) education dates back to the 1990s (the acronym SMET was used by the National Science Foundation in the 1990s), it was widely studied only after the recent call made by the United States for change in the education system. Due to concerns about a decrease in enrolment in STEM majors (ICF and Cedefop for the National Academy of Science [NAS], 2007; National Research Council [NRC], 2012; European Commission, 2015) and the goal of producing a competitive workforce to increase prosperity (Australia Office of the Chief Scientist, 2014; National Association of Colleges and Employers, 2015; STEM Education Review Group, 2016; Turkey STEM Education Report; 2016), STEM education has been receiving increasingly greater attention all around the world. Similar issues have been shared by many other countries as well. For instance, it has been reported in the United Kingdom's (UK) STEM report that STEM subjects are closely related to the UK's economic success (Morgan and Kirby, 2016). Likewise, Ireland aimed to be a hub of technological creativity and a leader of innovation by providing the highest quality STEM education (STEM Education Review Group, 2016). To conclude, over the years, STEM has accordingly attracted attention in various countries (e.g., Australia, Thailand, Turkey, and the UK) (Australia Office of the Chief Scientist, 2014; Bissaker, 2014; ICF and Cedefop for the European Commission, 2015; Teo and Ke, 2014; The Scottish Government 2017; Turkey STEM Education Report, 2016).

To increase the number of learners subsequently adopting STEM-related jobs, to train competitive citizens, and foster children's understanding of how to use STEM disciplines in solving daily-life problems, a fundamental change in education is essential. However, “[t]raditional classroom lecture methods are not preparing our youth for the challenge of the coming global change” (Koehler et al., 2016, p. 13). In addition to those issues raised, there is also a need to train learners as problem solvers, to provide learners with an understanding of how STEM disciplines are used to solve daily issues, and to help learners relate to school and daily-life, an integrated STEM approach is necessary (Furner and Kumar, 2007).

Although considerable emphasis was placed on the necessity of change with regard to integrated STEM education, very little effort has been devoted to how to train teachers to implement it in K-12 classrooms (Rinke et al., 2016) due to uncertainty associated with integrating STEM education and how to implement it in the most effective way. In other words, there are few research studies on how to develop teachers’ knowledge and practice for integrated STEM implementation. However, for integrated STEM reform to succeed, it is very important to focus on what teachers and PSTs need to know to implement integrated STEM education effectively.

Regarding studies of teacher knowledge and practice, it is widely accepted that PCK is an essential body of knowledge that is a unique mixture of content and pedagogy for supporting learners’ understanding (Shulman, 1987). Research has revealed that teachers’ understanding of integrated STEM is generally superficial (Ring et al., 2017). Furthermore, teachers have difficulty in implementing integrated STEM education, especially with regard to integrating engineering (Lau and Multani, 2018) and engineering design (Roehrig et al., 2012) into science and mathematics. Given that only limited research has been conducted with teachers, “[v]ery little research exists on how to most effectively prepare preservice teachers for STEM-infused classrooms” (Rinke et al., 2016, p. 301). Successful implementation of integrated STEM education starts with and depends mainly on enriching PSTs in terms of skills, knowledge bases, and experiences (Stohlmann et al., 2012). To address the gap noted by Rinke et al. (2016), PCK, a well-known framework for teaching and teacher training (Abell, 2007), would likely be useful. To conclude, in this study we aimed to provide training and develop a model that fosters PSTs’ PCK for integrated STEM implementation and examined its contribution to the participants’ PCK for integrated STEM development.

Conceptual framework

In this part of the study, first, integrated STEM education, engineering and design process, and features of STEM implementation will be introduced. Later, (PCK) construct will be explained. Then, what PCK for integrated STEM means will be focused on. Finally, in light of the gap identified in the literature, a training program for developing PCK for integrated STEM will be provided.

Integrated STEM education

Integrated STEM education has been defined in various ways by researchers. While Bryan et al. (2015) defined integrated STEM education as “the teaching and learning of the content and practices of disciplinary knowledge which include science and/or mathematics through the integration of the practices of engineering and engineering design of relevant technologies” (p. 24), Kelley and Knowles (2016) suggested that it is “the approach to teaching the STEM content of two or more STEM domains, bound by STEM practices within an authentic context for the purpose of connecting these subjects to enhance student learning” (p. 3). In a recent paper, Martín-Páez et al. (2019) stated that “STEM teaching must be based on the standards of STEM curricula, creating experiences for students to allow them to develop STEM proficiency. These experiences should include participation in research, logical reasoning, and problem solving” (p. 803). Finally, Sanders (2009) stressed that including all STEM disciplines in a lesson is not obligatory; rather, integrating at least two STEM disciplines into a lesson is enough for being an integrated STEM teaching. In light of different views of STEM, in this study, we synthesized an integrated STEM definition that includes the integration of at least two STEM disciplines in an authentic context to solve a daily-life problem/challenge involving chemistry (e.g., thermos design, voltaic cell design with the highest voltage, designing a fire extinguisher) using science and/or mathematics concepts through an engineering design process supported by technology. The integration of the disciplines is highlighted due to its usefulness in providing “more relevant, less fragmented, and more stimulating experiences for learners” (Furner and Kumar, 2007, p. 186). Additionally, it helps learners become better problem solvers (Stohlmann et al., 2012). Moreover, “[th]e motivation to integrate STEM is, in part, driven by workforce talent needs. Currently, the STEM that happens in research, industry, and society tends to reside at the integrated end of the spectrum” (Nadelson and Seifert, 2017, p. 222). In this study, we paid specific attention to integrating all STEM and STEM+ disciplines into our training. Additionally, the dominant STEM discipline was chemistry (i.e., science).

Engineering and engineering design process

The National Academy of Engineering [NAE] (2010) defined engineering design as an “iterative process that begins with the identification of a problem and ends with a solution that takes into account the identified constraints and meets specifications for desired performance” (p. 6–7). In integrated STEM education, students are offered the opportunity to practice real-world problems that encourage the use of inquiry skills through a design process to achieve an appropriate solution (Wang et al., 2011). Furthermore, engineering practices create an ideal way to integrate STEM into science education through engineering design (National Academy of Engineering and National Research Council [NAE & NRC], 2009; NRC, 2012). Additionally, engineering and design processes also provide students with the opportunity to engage in a real-world context to learn science, develop their problem-solving, communication and team working skills, and abilities (Roehrig et al., 2012). Therefore, engineering design is one of the most widely used approaches adopted when including engineering, mathematics, and technology in scientific content.

Features of integrated STEM education implementation

Given the lack of consensus on the definition of integrated STEM education, Srikoom et al. (2018) stated that “[o]ne of the biggest educational challenges for K-12 STEM education is that few general guidelines or models exist for teachers to follow regarding how to teach using or applying STEM integration approaches in their classroom” (p. 2). Moore et al. (2015) stated that integrated STEM implementation should include (i) a meaningful context that motivates learners, (ii) an engineering design process that helps learners develop 21st-century skills (e.g., higher-order thinking skills), (iii) redesign that provides an opportunity for learners to learn from failure, (iv) challenges and/or daily-life problems based on standards in the curriculum, (v) a learner-centred conceptual learning environment, and (vi) teamwork and communication. In addition to this already comprehensive list, Teo and Ke (2014) added that integrated STEM implementation should include more formative assessment. Moreover, project-based, problem-based and inquiry-based approaches could possibly be used in integrated STEM implementation (Wang et al., 2011; Kennedy and Odell, 2014). Finally, at least two or more STEM disciplines and whenever possible other non-STEM disciplines (e.g., art) should form part of the integrated STEM implementation (Sanders, 2009; Kennedy and Odell, 2014).

PCK

PCK was coined by Shulman (1986) and described as a “special amalgam of content and pedagogy that is uniquely the province of teachers” (Shulman, 1987, p. 8). PCK is a specialized knowledge that teachers utilize while transforming subject matter knowledge into a more understandable form for students. In the literature, a number of scholars have modelled PCK in different ways over the years (e.g., Grossman, 1990; Magnusson et al., 1999; Gess-Newsome, 2015; Carlson and Daehler, 2019). One of the most widely used models was proposed by Magnusson et al. (1999). In this model, PCK has five components, namely, orientations to science teaching, knowledge of the learner, knowledge of the curriculum, knowledge of instructional strategies, and knowledge of assessment. In this study, we focused on four components, namely, knowledge of learner, instructional strategy, curriculum, and assessment, all of which have been commonly included in PCK models since the introduction of the PCK framework itself. We did not include the orientations to science teaching component due to difficulties in defining and measuring the orientations of teachers (Friedrichsen et al., 2011).

PCK for STEM

PCK for STEM requires teachers to design a STEM-based lesson plan, implement it, and help learners use scientific and mathematical knowledge in their designs, which teachers then need to develop (Vossen et al., 2019). PCK for integrated STEM requires teachers “know-how to meld engineering and their disciplines effectively in classroom instruction. Teachers must have the pedagogical content knowledge, or PCK, to help them expand beyond science or mathematics to include defining and delimiting engineering problems, designing solutions, and optimizing designs” (Lau and Multani, 2018, p. 196). To help the reader understand what we mean by PCK for integrated STEM, we have defined PCK components for integrated STEM (Table 1). Research has revealed that teachers have experienced various difficulties in integrated STEM implementation, for instance, difficulty in integrating other STEM subjects (e.g., engineering and technology), especially those outside their own areas of expertise (Roehrig et al., 2012; Shernoff et al., 2017; Lau and Multani, 2018; Alan et al., 2019). Moreover, although integrated STEM requires an increased use of formative assessment (e.g., use of poster presentations of learners’ research and design, rubrics for learners’ products and group work), teachers experience obstacles to how to use them. Additionally, teachers have had problems adjusting to ‘flexibility’ in the design process that allows multiple solutions and products to be possible. Yet another struggle was noted in terms of teachers’ general inability to create authentic context involving daily-life problems (Teo and Ke, 2014).
Table 1 The details of PCK for STEM components
PCK for STEM components Details
Learner Teachers’ knowledge about possible difficulties learners may face during the design of a product or the use of a scientific concept for design, and alternative concepts that may hinder their learning and/or design of a product
Curriculum Teachers’ knowledge about goals and objectives relating to STEM in the curriculum and curricular goals for STEM education
Instructional strategy Teachers’ knowledge of strategies implemented through integrated STEM class (e.g., inquiry-based or problem-based STEM) and strategies for design teaching (e.g., ‘studying prior art’ strategy for knowledge-based design (Crismond and Adams, 2012))
Assessment Knowledge of assessment techniques for assessing learners’ efforts through both the process (e.g., completing a design log), and the products that they design (e.g., an airbag or an earthquake-resistant building)


Recently, Alonzo and Kim (2015) categorized PCK as declarative versus dynamic. While declarative PCK is the knowledge utilized in the formation of instruction plans, dynamic PCK is the knowledge that a teacher utilizes during teaching. A recent model of PCK proposed by Gess-Newsome (2015) made another PCK categorization and mentioned personal PCK (i.e., PCK that is specific to a teacher and that is developed by a teacher owing to his/her personal experience) and collective PCK (i.e., PCK that is formed by a group of teachers) (Carlson and Daehler, 2019). In this study, we studied 13 PSTs’ declarative and personal PCK for STEM.

Closing the gap

Given the importance of integrated STEM teacher education, calls highlighting the significance of STEM teacher preparation, and the scarcity of longitudinal studies on PSTs’ PCK for STEM development (Lau and Multani, 2018; Vossen et al., 2019), this study aimed to design a training program and then form a model for developing PCK for integrated STEM. The researchers think that both the results and the model based on the results will fill the gap in the literature and provide evidence for how to support teachers’ PCK for integrated STEM development. In doing so, we aim to enrich PSTs’ knowledge and experience in integrated STEM implementation before they start the profession. Due to the long-lasting nature of PCK development, teacher education programs could be accepted as the first steps for this development. The PCK that PSTs gain through teacher education programs has a crucial role in their teaching careers. Hence, we feel that when PSTs are enriched with strong PCK for teaching integrated STEM, this will allow for more effective implementation of integrated STEM in their future classrooms (Vossen et al., 2019). In the STEM field, most of the studies were conducted with K-12 students, therefore, “very little research exists on how to most effectively prepare preservice teachers for STEM-infused classrooms” (Rinke et al., 2016, p. 301). To conclude, this study is going to present rich data collected through multiples sources and over a long time, and could thus act as a model for other integrated STEM teacher education programs.

Research-based practices provided in the training

The authors of the study designed a training program in light of the useful guidelines reported in the literature on how to augment teachers’ PCK for integrated STEM development. Although the previous studies were on PCK development, we used them for PCK for integrated STEM development.

First of all, subject matter knowledge (SMK) is an essential knowledge base for PCK development (Shulman, 1987), which enlightens us in the sense that PSTs have to have SMK for all STEM disciplines. However, it has been noted that teachers’ engineering SMK is somewhat limited (Ring et al., 2017). Therefore, PSTs have to learn about engineering and engineering design processes, and this was addressed in the training designed. Moreover, PSTs should be aware of what PCK is due to the utility of explicit PCK use in teacher education (Nilsson and Loughran, 2012; Aydin et al., 2013). In addition to engineering and design processes, an introduction to PCK was also given as part of the first step. Regarding this step, our participants had taken Information and Communication Technology I & II, and Technology Integration for Chemistry Instruction courses before the study. Regarding mathematics, they had taken Calculus I & II, and Mathematics for Chemists courses earlier. In other words, the participants in this study have adequate knowledge bases for technology and mathematics when compared with the engineering discipline. They have never taken any engineering course. Due to that reason and the time constraints (i.e., this course is an elective course for one semester), we preferred not to stress technology and mathematics in the training, but this does not mean that technology and mathematics were ignored in other elements of the training. In a different case, the learning cycle may include those STEM disciplines as well.

Second, active participation in activities is one of the vital sources of teachers’ learning (Desimone, 2009). Rather than being passive listeners, teachers should take an active role in the process, experiencing activities to be familiar with the possible difficulties that learners may face. Regarding this issue, Grossman (1990) also highlighted that “…teachers replicate the strategies they experienced as students” (p. 10). Hence, experiencing integrated STEM activities as if they were K-12 learners would provide valuable information about the possible problems that learners may have and/or possible ideas that they devise to design the product in the STEM activity. Given the importance of such experience, we provided six integrated STEM activities through which PSTs have a chance to experience integrated STEM (the details of the activities will be provided in the Methodology section).

Third, research has also revealed how professional support contributes to PSTs’ PCK development (Van Driel et al., 2002; Hanuscin and Hian, 2009). Van Driel et al. (2002) noted that studying with mentors helped PSTs develop awareness of both learners’ difficulties and alternative concepts; moreover, PSTs enriched their instructional strategy repertoire. Mentoring support provides an opportunity for PSTs to reach the same level as their mentors’ own knowledge and experience (Mena et al., 2017). Although mentoring support can be offered in different ways (e.g., face-to-face, online) and with different roles (e.g., directive, encourager) (Feiman-Nemser, 1998; Mena et al., 2017), we integrated face-to-face mentoring with an encourager as well as non-directive roles into the training.

Finally, Nilsson (2008b) stated that reflection helps PSTs “develop deeper insights into their understandings of science teaching and learning” (p. 1282). By reflecting on what they have learned and experienced, PSTs will have the chance to make their tacit beliefs, experience, and knowledge explicit, which catalyses PCK development (Loughran et al., 2004). To conclude, the training offered includes emphasis on SMK, active participation in the activities, studying with mentors, and reflecting on own development and learning. The training designed in this study could be used for the professional development of non-STEM teachers as well. However, putting emphasis on all features of integration of STEM education (as mentioned above) and integrating STEM disciplines through all cycles make this training specific to PCK for integrated STEM education.

To clarify, providing engineering knowledge in the first cycle, offering many STEM activities that integrate STEM disciplines, analysing strong and weak STEM lesson plans that are aimed at integrating STEM disciplines with mentors, and asking PSTs to reflect on their learning not only on science but also on engineering and other STEM disciplines ensure that the training designed in this study is specific to integrated STEM teacher education.

The research questions directing the study were:

(1) How does participants’ PCK for STEM develop through a 13 week training program based on research-based practices?

(2) How did research-based practices contribute to PSTs’ PCK for STEM development?

Methodology

Research design

The current study is qualitative in nature which means that “qualitative researchers study things in their natural settings, attempting to make sense of, or to interpret, phenomena in terms of the meanings people bring to them” (Denzin and Lincoln, 2005, p. 3). The study aimed to investigate PSTs’ PCK for integrated STEM development with qualitative lens.

Context of the study

Thirteen junior PSTs (10 females, 3 males) participated in the study. All participants were informed about the purpose of the study. The participants were enrolled in the elective STEM course offered at the sixth semester of an eight-semester chemistry teacher education program (i.e., four years). By the sixth semester, the participants had taken chemistry courses (e.g., analytical chemistry, organic chemistry), pedagogical courses (e.g., classroom management and instructional strategies, and curriculum), and PCK courses (e.g., use of technology in chemistry education, and alternative concepts in chemistry). None of the participants had taken integrated STEM or interdisciplinary STEM courses before this course.

In this study, focus was placed on PSTs’ PCK for integrated STEM development using a 13-week training course based on research-based practices. As teacher educators, we recognize the utility of iterative training when developing PCK. Therefore, the training provided during the course is iterative in nature (see Appendix 1 for the course details), and this is consistent with the notion that PCK development requires considerable time and effort (Gunckel et al., 2018).

In our context, the integrated STEM elective course was offered by the Chemistry Teacher Education Department. Hence, the dominant discipline in this study was chemistry. Moreover, as mentioned earlier, this study is an example of context integration of STEM research (see Integrated STEM Education above). To help chemistry PSTs learn how to integrate chemistry with other STEM disciplines, be aware of the daily-life problems (e.g., preventing apples’ browning, preventing heat transfer), tools or materials related to chemistry concepts (e.g., fire extinguisher, airbag, toothpaste, polymers, cells), and how to use chemistry concepts in design (e.g., the ways of heat transfer should be known and those ways should be prevented to ensure heat isolation), and how to use mathematics and technology in design based on chemistry knowledge, we applied six integrated STEM activities through experience cycles. In the mentoring sessions (the mentors each have a PhD in Chemistry Education and are the authors of the paper), we also used chemistry-based STEM activities from STEM webpages, STEM projects, or from the Internet. In each session, we examined the existing STEM lesson plan regarding chemistry concepts used in design, the possible ideas that K-12 learners may come up with, chemistry, and other STEM disciplines’ curriculum objectives related to the activity. Moreover, mentors paid specific attention to make the participants see the connections between chemistry and other STEM disciplines in those mentoring cycles. Finally, in the reflection part, the PSTs were asked to reflect on their experiences in the experience and mentoring sessions regarding chemistry content knowledge, use of chemistry knowledge in the design process, and technology-chemistry or chemistry-mathematics integration as well as PCK development for integrated STEM.

Data collection

The data were collected through multiple sources in the forms of Content Representation (CoRe), semi-structured interviews, and reflection papers to capture the participants’ PCK for STEM. All data collection materials were applied in Turkish. The participants’ responses were then translated into English independently by three researchers who were fluent in both Turkish and English. They worked on it until consensus was reached on translation. The timeline for data collection is summarized in Fig. 1.
image file: d0rp00074d-f1.tif
Fig. 1 Timeline of data collection.
The CoRe. The CoRe developed by Loughran et al. (2004) was used as a lesson plan to portray PSTs’ PCK for integrated STEM development. The CoRe is a matrix including big ideas addressed in columns. The questions (e.g., difficulties/limitations connected with teaching the big idea) corresponding to PCK components (e.g., knowledge of learner) are in the rows. In the intersection of each row and column, PSTs are expected to answer each question for the particular big idea set above. The participants were asked to prepare a CoRe showing the details of an integrated STEM lesson at both the beginning and end of the course as an assignment. The PSTs were informed that they could use any sources to prepare the CoRe individually. An example of a CoRe prepared by Julie is provided for readers in Appendix 2.
Semi-structured interviews. These were conducted at the end of the course to examine the contribution made by the research-based practices to the participants’ PCK for integrated STEM. Pre-interviews were not conducted because the PSTs had not participated in any integrated STEM course previously. Ten out of 13 participants volunteered to hold interviews with the researchers after their training. Each interview lasted approximately 30 minutes. All the interviews were audio-recorded and subsequently transcribed verbatim. Sample interview questions were:

(1) Which components of the course contribute to your professional knowledge as a teacher in terms of integrating STEM into your future lessons?

Probing question: How did … help you develop your PCK for STEM? Please explain.

(2) Did you notice any improvement in your use of curriculum and learning goals while preparing STEM lesson plans through the course? If yes, how?

Probing question: What could the possible sources that contributed to that improvement be? Please explain how they influenced that improvement.

Reflection papers. Furthermore, to support the data collected via CoRes and interviews, reflection papers were collected at the end of each week as additional data. There were nine questions in each reflection paper. Sample questions are as follows:

(1) During this activity, at which points might learners have difficulties? Why do they have those difficulties? Please explain.

(2) Which instructional strategy would you implement for this integrated STEM activity if you were a teacher? Why?

(3) During this activity, what did you learn about the integration of STEM disciplines? What else could be integrated into the activity? Please explain.

During each of the integrated STEM activities, a design log was given to each group. Although different engineering design models exit, we used Wheeler, Whitworth, and Gonczi's (2014) model due to the clarity of its steps and the fact that it provides probing questions (e.g., What do you think about the materials that can be used in this activity?) for each step of the design process. The model included six steps, namely brainstorming, research, design, constructing and testing, redesigning, and evaluation. The design logs provided details about how the participants went through the engineering design process (i.e., how they did research for design, etc.). Therefore, design log data were not analysed in this study, which focuses on PCK development for integrated STEM.

Ethical issues. All the PSTs signed a consent form and knew that they could withdraw at any point during the study. Data collected for this study were not part of the course grading. Moreover, details about the research were provided to the Head of the Department and the Dean of the College of Education. Necessary ethical approval and permission from the Institutional Review Board were also obtained from Van-Yuzuncu Yil University, Ethical Board of Social Science and Human Subjects. Pseudonyms are used in this study to preserve the confidentiality of the participants.

Data analysis

During the data analysis, researchers performed an iterative process. First, the data were read to gain insight into them. Then, a draft code list was developed based on the components of PCK and the basic features of integrated STEM education. Then, three participants’ pre- and post-CoRes were read and coded by researchers independently. Later, researchers came together, compared and contrasted their codings, and discussed discrepancies until they reached a consensus. Moreover, in this meeting, the draft code list was also revised and enriched with new codes derived from the first round of data coding. In other words, during the data analysis, we employed both deductive (i.e., using existing codes from components of the PCK model such as learners’ difficulties in understanding a particular chemistry concept and use of instructional strategies) and inductive (i.e., creating new codes such as starting STEM activity with a daily-life problem) methods (Patton, 2002). Then, we coded the other two participants’ pre- and post-CoRes with the revised code list and came together again. In the second round, the discrepancies were found to be minimal, and the code list was sufficient. To increase the reliability of the procedures that the researchers have gone through, intercoder agreement (or cross-checking) should be provided (Creswell, 2017). Therefore, we compared and contrasted two coders’ coding by the use of Miles and Huberman (1994) formula, which is:
Agreement % = Number of agreements/(Total number of agreements + disagreements) × 100.

Intercoder agreement was calculated as 0.94, which is higher than the 0.80 value set by Miles and Huberman (1994). Then, the remaining data were coded by employing the final version of the code list (Table 2).

Table 2 Final version of coding scheme for PCK for integrated STEM
PCK components Codes
Curriculum Learning objectives
Setting goals for teaching only science content
Setting goals for teaching at least two STEM disciplines (e.g., setting goals for both science content and design processes)
Learner Difficulties
Learners’ difficulties with only science content
Learners’ difficulties with both science content and generic difficulties related to other STEM disciplines
Learners’ difficulties with both science content and other STEM disciplines
Alternative conceptions
Learners’ alternative conceptions about science content
Learners’ alternative conceptions about science content and generic difficulties related to other STEM disciplines
Learners’ alternative conceptions about both science content and other STEM disciplines
Instructional Strategy Teaching strategies
Implementing alternative teaching strategies (e.g., argumentation, inquiry and project-based learning) for teaching a science topic
Implementing alternative teaching strategies (e.g., argumentation, inquiry and project-based learning) for STEM to address a problem or design challenge
Implementing teaching strategies specific to engineering design (e.g., reverse engineering)
Assessment What to assess
Assessing learners’ understanding of science content only
Assessing both learners’ understanding of science and other STEM disciplines but with emphasis on science
Assessing both learners’ content understanding and other STEM disciplines with equal emphasis
Assessing learners’ product/design process using criteria lists
Assessing learners’ product/design process using a detailed rubric
How to assess
Use of traditional means of assessment such as tests or quizzes
Use of alternative assessment strategies such as oral or poster presentations or use of rubrics for determining best design


After coding the pre- and post-CoRes, we put all the codes together to form categories for PCK for integrated STEM (Patton, 2002). In light of the PCK literature (i.e., the definition of topic-specific PCK, PCK for integrated STEM, etc.) and the data, we saw that all the participants’ pre-CoRes had topic-specific PCK for teaching a chemistry topic that did not involve any daily-life problem, integration of other STEM disciplines, or addressing a design challenge. Then, when we put all post-CoRe data together, we realized that we had two PCK categories varying in their levels of sophistication, one of which was the desired one while the other had some issues in balancing four STEM disciplines. After discussions on the preliminary categories, we reached a consensus on the PCK categories (Table 3). Later, the CoRe data were triangulated by the data received from interviews and reflection papers (Patton, 2002).

Table 3 The details of the PCK categories formed
PCK components Category-1: PCK A Category-2: PCK B Category-3: PCK C
PCK for teaching a chemistry topic (TSPCK) Transitional PCK (less coherence among STEM disciplines) PCK for STEM (more coherence among STEM disciplines)
Curriculum Providing goals (big ideas) for teaching a chemistry topic only Providing goals (big ideas) for teaching a chemistry topic only Providing goals regarding at least two STEM disciplines
Learner Providing learners’ difficulties/alternative conceptions regarding learning a topic Providing learners’ difficulties/alternative conceptions regarding learning a science topic in detail and superficial description of learners’ difficulties/alternative conceptions regarding other STEM disciplines Providing detailed difficulties/alternative conceptions regarding learning a science topic and other STEM disciplines in detail
Instructional Strategy Implementing teaching strategies/representations for teaching a topic Implementing strategies for integrated STEM with some limitations (or with fewer STEM features) (e.g., use of unfamiliar daily-life problem) Implementing integrated STEM strategies (e.g., inquiry-based STEM) with extra ones for the other STEM disciplines (e.g., reverse engineering)
Assessment Assessing only learners’ understanding of content Assessing more science content understanding and other STEM disciplines superficially Assessing both science content understanding and other STEM disciplines sufficiently


Regarding the contribution of the training elements to PCK for integrated STEM development, we analysed the interview and reflection papers written each week. Specific examples of each element's support or statements about the aid of each element were determined. Then, the number of participants who pointed out the contribution of the elements to each of the PCK components was calculated, and statements showing how mentoring or reflection helped PSTs were selected to inform both teacher educators and the literature.

From Category A to Category C there was a transition from TSPCK to PCK for integrated STEM. PCK A represents PCK for teaching a chemistry topic. The participants in this category had general TSPCK. PCK B represents a transitional PCK with less coherence among STEM disciplines (i.e., more emphasis on science content). In this category, the participants mentioned only their goals for teaching a science (i.e., chemistry) topic. Although they did not set any goals for other STEM disciplines, their CoRes included the integration of other STEM disciplines, and this shows a conflict between goals set and lesson content. Finally, PCK C has more balance among STEM disciplines. The learning goals in this category focused not only on science content but also on other STEM disciplines. Additionally, learners’ difficulties regarding all STEM disciplines were provided in detail. Moreover, the participants planned to implement integrated STEM strategies sufficiently.

Results

First, PCK for integrated STEM development was provided for each PCK component. Then, the contribution of the training based on research-based practices to PCK for integrated STEM was presented. Table 4 presents a summary of PCK for integrated STEM development observed.
Table 4 Number of PSTs by PCK categories from pre-CoRe to post-CoRe
  PCK A PCK B PCK C
PCK for teaching a chemistry topic (TSPCK) Transitional PCK (less coherence among STEM disciplines) PCK for STEM (more coherence among STEM disciplines)
a Pseudo names were used.
Before training All participants (n = 13) None None
After training None Five (n = 5) (Ella,a Naomi, Samuel, Sandra, Michelle) Eight (n = 8) (Alice, Caroline, Charles, Emilia, Emily, Felix, Julie, Nicole)


All the PSTs planned a lesson for teaching a chemistry topic at the beginning (i.e., PCK A). However, after taking the course, only eight PSTs were able to balance STEM disciplines in post-CoRe (i.e., PCK C). The other five PSTs were able to move from TSPCK to PCK for integrated STEM view but encountered difficulties in ensuring coherence between STEM disciplines (i.e., PCK B). The details of development for each PCK component are presented below.

Knowledge of curriculum

Knowledge of curriculum is related to the goals teachers set for students’ learning in a plan and/or lesson. The participants established goals about learning a specific chemistry (i.e., science discipline) concept in the pre-CoRe (PCK A). Typical goals included in this category were “The rate of a chemical reaction is the change in concentration of reactants per unit time” (Caroline), and “The particles of matter move consistently” (Emilia). In the post-CoRe, after 13 weeks of PCK for STEM training, eight of the participants became aware of setting goals for the design process (PCK C). Although the remaining participants (n = 5) did not establish design goals (i.e., engineering discipline), they did include the design process in the post-CoRe (PCK B). For instance, Samuel set “In oxidation–reduction reactions, electrons are transferred from one substance to another” as a main idea to address. However, he included a challenge to design a bell for irrigation by devising a voltaic cell with the highest voltage in the post-CoRe. Typical PCK B plans showed that participants in this category do not realize the inconsistencies between knowledge of curriculum and knowledge of the instructional strategy components of PCK for integrated STEM. By contrast, the PSTs in PCK C, in addition to setting chemistry content goals, also established goals for other STEM disciplines (e.g., engineering design process or mathematics). For instance, Emily's post-CoRe aimed to address two main ideas (i.e., goals), namely, “Chemicals are everywhere in daily life” and “Designing your own natural soap is possible with chemistry.” This emphasized both a design goal and chemistry content goal for learning specific chemistry concepts. Likewise, Alice set “Gases are described by pressure, volume, temperature, and mole numbers” and “A hot air balloon design: the hot air inside the balloon is less dense than the surrounding air” as goals in the post-CoRe. In addition to the science and design goals set, she set “Drawing graphs of Gas Laws by use of existing data set” (i.e., goal set for mathematics discipline).

Knowledge of learner

This component is related to teachers’ knowledge about learners’ difficulties and alternative conceptions of the STEM disciplines. The analysis of the participants’ pre-CoRes revealed that all the PSTs were aware of learners’ difficulties and alternative conceptions of the chemistry content they concentrated on (PCK A). For instance, Nicole planned a lesson on states of matter. She stated that learners might have difficulty in imagining and understanding the particles of matter due to the abstract nature of the topic. Moreover, she claimed that learners might think: “Gases cannot be compressed,” “Evaporation starts with boiling,” and “Water disappears after evaporation,” which are alternative conceptions related to the topic focused on in pre-CoRe. Similarly, Sandra stated that students might think that the atomic number of an atom is equal to its atomic mass. Finally, Michelle planned a lesson on the interactions among chemical types. Concerning the alternative conceptions that learners might have she wrote: “The NaCl molecule is the smallest particle of NaCl compound” and “Molecules of soft materials are also soft” in pre-CoRe.

The analysis of the participants’ post-CoRes revealed that after being involved in PCK for STEM training, the PSTs started to consider learners’ difficulties and alternative conceptions regarding both the chemistry topic and other STEM disciplines in detail (PCK B and C). Five PSTs categorized in PCK B noted learners’ generic difficulties and alternative conceptions (i.e. difficulties/alternative conceptions are not specific to the engineering design process included in the CoRe). However, those five PSTs included difficulties and alternative conceptions specific to chemistry content focused on in the CoRe. For instance, Ella planned a lesson on gas properties and included the challenge of designing the fastest car through the use of gas properties. She stated that learners could have difficulty in creating a design by using the materials provided, which does not state a specific difficulty related to the challenge.

In the post-CoRes, eight of the participants provided detailed descriptions of learning difficulties and alternative conceptions specific to the chemistry content and other STEM disciplines. For instance, Julie focused on designing a water purification system through the use of the concept of intermolecular forces in chemistry. In her post-CoRe, she provided various alternative conceptions about intermolecular forces that students might have. Moreover, she noted, “It might be difficult for learners to understand how van der Waals forces arise between impurities and how a purification system works” as a learning difficulty that is highly specific to the water purification system design she planned. In another example, Felix stated that learners might have difficulty in drawing graphs showing relations among gas properties (i.e., drawing a graph showing pressure-volume relation).

Knowledge of instructional strategy

The analysis of the pre-CoRe showed that all the participants focused only on teaching chemistry topics (PCK A). For instance, Samuel planned to teach chemical bonding as a topic and intended to explain it through the use of visual representations. Similarly, Caroline prepared a CoRe to explain the main concepts of the rate of chemical reactions (i.e., rate, order of a reaction, activated complex, etc.).

At the end of the training, it was found that the PSTs were able to integrate basic features of STEM education within the post-CoRes. In PCK B, an emphasis on basic features of integrated STEM education was determined to some extent. However, these PSTs encountered certain difficulties in identifying a real-life problem, using a design challenge, and integrating other STEM disciplines into science (PCK B). For instance, Michelle stated, “Why do hydrangeas turn blue in acidic soil?” and Sandra wrote, “What liquid works best in making invisible ink?” as problems to be addressed in the post-CoRes; these were not real-life problems. Also, learners in high schools are not particularly familiar with these concepts. Furthermore, in PCK B, the participants implemented at least one appropriate strategy for teaching integrated STEM such as argumentation, inquiry, and project-based learning. For instance, Sandra planned to implement argumentation and stated that learners would work in groups in the post-CoRe. She would ask each group to brainstorm and identify their claim accordingly. Then, groups would create their design based on their claim. After testing the designs, she would give them a chance to evaluate and redesign.

After the training, the PSTs (n = 8) in the PCK C group proposed a real-life problem that learners were familiar with. For instance, “Design a green, clean and eco-friendly detergent to protect both ourselves and nature” (Emilia) and “Design a water purification device/system” (Julie). Moreover, the participants in PCK C planned to implement an instructional strategy specific to informed design teaching in addition to other instructional strategies (e.g., inquiry). For instance, Julie prepared a CoRe based on designing a water purification system that was related to the intermolecular forces unit taught in the ninth grade. She planned to employ design-based instruction in her post-CoRe. In the research phase of the design process, she planned to use the ‘build knowledge through research’ design strategy and ‘reverse engineering of existing products’ in addition to argumentation. She wrote, “The teacher could bring a water purification system and investigate the components and working principles of the device with the students.” Likewise, Caroline enriched her instruction with informed design teaching. Her post-CoRe was oriented around finding a solution to cleaning and polishing the silver used in our daily lives. In the design phase, she asked learners to explain their designs utilizing the ‘understand the challenge’ design strategy by describing how the preferred design solution should function. In her post-CoRe, after feedback had been given, she would give learners the opportunity to revise their designs and write the positive and negative sides of the designs using a decision diagram, which is part of the ‘weighing options and making decisions strategy’ (Crismond and Adams, 2012). These examples revealed that the participants in PCK C utilized more than one instructional strategy compatible with the engineering design process. Table 5 summarizes the details of the instructional strategy component in the post-CoRes.

Table 5 The details of the instructional strategy component in post-CoRes
  PST Science content/topic Engineering design challenge Instructional strategy used
Transitional PCK (PCK B) Ella Properties of Gases & The Gas Laws Design the fastest car Inquiry-based STEM
Naomi Graham's Law: Diffusion and Effusion of Gases Design a natural perfume with a minimal chemical composition Project-based STEM
Michelle Acids and Bases Why do hydrangeas turn blue in acidic soil? Argumentation-based STEM and Give explanations for design choices strategy
Samuel Electrochemistry Design a bell for irrigation Inquiry-based STEM
Sandra Chemical Reactions What liquid works best for making invisible ink? Argumentation-based STEM
PCK for STEM (PCK C) Nicole Intermolecular forces Design a glue stick Argumentation-based STEM and Studying prior art and virtual drawing
Caroline Redox reactions Cleaning and polishing silver Argumentation-based STEM, describe how preferred the design solution should function and behave and decision diagrams
Emily Chemistry in everyday life Design a natural soap Argumentation-based STEM
Charles Polymer chemistry Design a diaper that absorbs most of the liquid. Inquiry-based STEM
Alice Properties of Gases & The Gas Laws Design a hot air balloon that stays in the air the longest Argumentation-based STEM
Julie Intermolecular forces Design a water purification device/system Argumentation-based STEM and reverse engineering
Emilia Chemistry in everyday life Design green, clean and eco-friendly detergent Argumentation-based STEM
Felix Properties of Gases & The Gas Laws Design an irrigation system Inquiry-based STEM


Knowledge of assessment

The analysis of the participants’ pre-CoRes revealed that all the PSTs aimed to assess learners’ understanding of the chemistry content focused on PCK A. For instance, Michelle planned a lesson on the concept of chemical bonding in pre-CoRe and stated that she would use a concept map to determine the extent to which learners were able to relate to the concepts in the topic of chemical bonding (e.g., molecule, ion, electronegativity). Additionally, she would assess to what extent learners were able to determine the bonds that the example compounds included. Likewise, Emilia stated that she would ask learners to draw the molecular structures of daily-life chemicals (e.g., water) in the solid, liquid, and gas phases, including the particles themselves and the space between them. Both examples were intended to assess learners’ understanding of content rather than the design process.

In the post-CoRe, the results showed that the PSTs who received PCK for integrated STEM training either planned to assess both learners’ understanding of science/chemistry and other STEM disciplines, but with an emphasis on science content (PCK B), or assessed both science content understanding and other STEM disciplines with equal emphasis (PCK C). A typical assessment strategy in transitional PCK (PCK B) included details and examples as to how to assess learners’ understanding of the chemistry content. For instance, Ella responded to the question of assessment in the CoRe by stating:

I ask learners to explain the relationships between gas pressure, temperature, and volume. I also ask them to give examples of the use of gases in our lives regarding their properties. I also pay attention to whether the groups’ hypotheses support their design or not. Moreover, I use a rubric for design.

Rather than providing the details of the criteria used for determining the successful design and details of the data received from the hypothesis-design relation, Ella paid greater attention to assessing learners’ understanding of the chemistry content. This PCK B response placed greater emphasis on learners’ understanding of the concepts of the chemistry content and less emphasis and less detail on assessing other STEM discipline knowledge or competencies (e.g., paying less attention to assessing learners’ performance during the design process.)

In the post-CoRe, eight of the participants concentrated on assessing both the understanding of the chemistry content and other STEM disciplines. For instance, Julie stated that she would ask why active carbon is used in purifiers and also asked learners to give examples of daily-life events involving the interaction of forces. Moreover, she would assess the learners’ answers as to the reason for the modifications made in the redesign process by linking the reason to the topic of intermolecular forces. Finally, she prepared a rubric for determining the best purifier design (i.e., with cost, the time necessary for the purification of 1 L of water criteria). In this typical assessment, the participants were able to assess both the chemistry content necessary for purifier design and the performance with regard to designing the product. Likewise, in his post-CoRe (i.e., CoRe on designing a diaper polymer) (Table 5), Charles wrote that in addition to a rubric for the diaper polymer design (e.g., with absorbency capacity, cost, endurance criteria), he would ask the groups to prepare a poster that included the group hypothesis (i.e., he prepared an inquiry-based STEM plan), the dependent and independent variables in their design, the test results, and a logo for the product. Different than the other participants in the PCK C category, Caroline and Emilia prepared a budget list to address the cost criterion of the product design. In other words, both participants aimed to assess learners’ budget calculations. As can be seen from the examples, the participants with PCK C planned to implement more and varying formative assessment strategies to assess learners’ design skills, mathematics, and use of chemistry knowledge in the design in a coherent manner.

The contribution of the training to PCK for integrated STEM

To determine the PSTs' opinions about the contribution made by the training, we focused on the interviews and reflection papers in addition to the CoRe data (Table 6).
Table 6 Sources contributing to PSTs’ PCK for STEM development
Components Learn Experience Mentoring Reflection
✓: all PSTs mentioned, +: 5 or more PSTs mentioned, *: 3 or less PSTs mentioned the contribution made by the source (10 volunteer PSTs agreed to do an interview).
Curriculum   + + *
Learner   +
Instructional strategy * + +
Assessment   + +
SMK * *  


Learning integrated STEM, engineering, and strategies for STEM and design. The participants mentioned that before the course they did not know anything about integrated STEM or integrated STEM implementation. In the interview, Julie noted that she did not have any idea about integrated STEM, but at the end of the semester, she had learned its essential features. Similarly, Naomi stated that she had learned how to integrate different STEM disciplines into her lessons. Samuel mentioned that although he took separate science and mathematics courses earlier, he had not taken any engineering-related courses, so he had very limited knowledge and views about engineering and engineering design. Thanks to this course, he learned the characteristics of engineering (e.g., including the re-design process). Similarly, Emilia and Michelle noted that the course had made them learn and think about engineering and engineering perspectives.

Regarding the contribution of learning cycles to instructional strategy implementation, Julie stated:

During the course, we received information about the strategies that can be used during integrated STEM implementation and experiencing them each week. Now, I can say that I can plan a lesson. I mean I can design a STEM activity and I can plan a STEM lesson that is project-based or argumentation-based or inquiry-based. I believe I can.

Moreover, in learning cycle-3, instructional strategies for informed design teaching and learning were presented. Although all the PSTs were unaware of the strategies introduced and discussed in terms of their implementation in the integrated STEM lesson, some PSTs (i.e., Michelle, Nichole, Caroline, and Julie) mentioned the contribution made by learning them. In the reflection paper written after learning cycle-3, Samuel noted that it might be useful to use the ‘understanding the problem’ strategy. He stated that he would ask learners to write the intended features of the thermos and state the criteria for the design, saying this would help them think about the design and research it further.

Experiencing six integrated STEM activities. Regarding the contribution made by experiencing STEM activities, the PSTs frequently noted its input to all PCK components. First of all, they noted having first-hand experience of a design process requiring integrated use of STEM disciplines. Caroline stated in the interview:

At the beginning, I did not have any idea about learners’ difficulties in STEM activities or alternative concepts that they might have. But, over the course, while doing the design each week, we observed that our designs have some drawbacks and result in an unsuccessful product. I mean, we experienced difficulties.

To be more specific, in her reflection paper, Caroline shared an interesting example of how experiencing the integrated STEM activities helped her. During the ‘Making a Bouncy Polymer’ activity, they thought that glue was a sticky material. Hence, the amount used in the polymer mixture should be higher than the amount of borax. At the end of the activity, they realized that this was not the case. Caroline mentioned that due to their experience, as a group they had a chance to learn about learners’ possible thinking. Likewise, Julie revealed that during the thermos design activity, she realized that she had confused the concepts of heat and temperature, so she thought that high school students might also be similarly confused by these same concepts. Similar to the learner component of PCK, experiencing project-, inquiry-, and argumentation-based STEM activities enriched their repertoire in knowledge of instructional strategy. During the interview, Nicole stated that they had a chance to participate in and experience STEM activities based on different strategies with different aspects (e.g., inquiry-based STEM activity required them to state a hypothesis for their design). Through experiencing the activities, the PSTs observed how to implement an integrated STEM activity based on these strategies. Correspondingly, the PSTs’ experience of the STEM activities augmented their knowledge about assessment as implemented in the integrated STEM lessons.

I did not know how to create a rubric before the class. Then, rubrics were used for each activity to evaluate groups’ designs, and sometimes to evaluate their claims or the hypothesis on which their designs were based. After a while, I realized I learned it [use of rubric] and I sometimes thought about possible criteria that might be included (Sandra, interview)

Finally, the PSTs revealed that participating in the six STEM activities supported their knowledge about what integrated STEM, engineering, and engineering design are, and indeed other disciplinary knowledge necessary for the design created each week (i.e., the PSTs conducted research each week to learn about the working principle of a rocket or fire extinguisher, etc.). For instance, none of the PSTs in this study had taken a polymer chemistry course. Regarding this point, Felix wrote in the reflection paper that they gained the chance to learn about polymers and their structure.

Studying with mentors. Studying with mentors throughout the course was the most frequently stated component of the training in terms of its contribution to the learners’ PCK for integrated STEM development. During the interviews, all the PSTs mentioned that mentoring sessions helped them develop PCK components. For instance, Julie claimed that she developed her abilities considerably with the help of her mentors. At the end of the course, she felt confident to plan an integrated STEM lesson because preparing lesson plans with mentors helped her develop knowledge about learners’ alternative concepts. The PSTs focused particularly on the improvement in their knowledge of assessment and knowledge of instructional strategies through the help of mentoring sessions. For instance, Samuel stated:

… at the beginning of the course, I did not know much about how to assess students’ understanding and how to implement instructional strategies for integrated STEM lessons. I learned so much from working with mentors while analysing the STEM lesson plans together.

Working with mentors also contributed to the PSTs’ development of knowledge of curriculum. They made progress in linking curriculum objectives with both science content and other STEM disciplines. Nicole stated that working with mentors helped them learn how to integrate curriculum objectives. Likewise, Caroline said in the interview:

While the curriculum objectives part was something that could be gained directly from the curriculum, we did not know how to use it. It seemed more difficult than it was, but when we examined “how should it be?” or “how should it not be?” with our mentors, we learned it in two or three weeks. It really helped me.

Reflection on own learning and performance. Reflection on all the practices provided and on own learning was stated as a contributing factor to PCK for integrated STEM. Emilia claimed that writing down her reflections helped her improve her PCK and made her start to think and act more scientifically during the course. With regard to knowledge of instructional strategies, the PSTs learned the use of different strategies during integrated STEM instruction. Alice claimed that writing down her reflections after each STEM activity helped develop her knowledge and use of instructional strategies. She said:

It asked [in the reflection paper] “Which instructional strategy, different than the one used here, would you implement for this integrated STEM activity if you were a teacher? Why?” I wrote that we learned to modify the activity. Let's say the activity is designed as argumentation-based STEM, I can now convert it into a project-based one.

Reflection also provided them with the means to increase their knowledge of assessment. They learned not only to assess what students learned but also their own performance in the design process. Most of the time, they used rubrics to assess the design process. Sandra stated that they did not know how to create rubrics before the integrated STEM course (i.e., the PSTs have not taken the Assessment Science Understanding Course yet). In the reflection paper, the PSTs were asked to find additional criteria that were different from the existing criteria provided by the course instructor for the STEM activity. Moreover, the quality of their rubrics developed over time as they continuously wrote down their reflections.

Discussion

This study aimed to examine the contribution of the training designed in light of the research-based practices for 13 PSTs’ PCK for integrated STEM development. Although STEM education has been frequently studied worldwide, there is a gap regarding how to educate teachers in integrated STEM implementation. To address the gap stated, we designed a training program providing emphasis on SMK, active participation in the activities, studying with mentors, and reflecting on the process, the benefits of which were determined in previous studies. In other words, although the practices are not new, the composition of the training program and the sequence of the practices that it includes are new and unique. Owing to the detailed reviews of integrated STEM, PCK, and teacher education literature and indeed our own experience in PST education, we came up with a novel model introduced herein. The PCK construct helped us to determine the components of a teacher's knowledge that should be developed for integrated STEM implementation. In light of the results of this research, we proposed a detailed model known as LESMeR, or Learn, Experience, Study with mentors, and Reflect on development, to inform the literature how to enrich and support PSTs’ PCK for integrated STEM development (Fig. 2).
image file: d0rp00074d-f2.tif
Fig. 2 The LESMeR model designed for PSTs’ PCK for STEM development.

Given diverse and promising practices iteratively over a 13 week period, the participants showed remarkable development (Appendix 3). Regarding the Learn element of the model, all the PSTs started the journey with little if any idea of what integrated STEM is or, indeed, how to integrate STEM disciplines into a lesson (i.e., PCK A, TSPCK for teaching a chemistry topic). Although the participants were more or less at the same level in terms of TSPCK at the beginning, they ended the journey with different PCK for integrated STEM levels (i.e., PCK B and PCK C). Five participants finished this journey with a transitional PCK that had less coherence among STEM disciplines. By contrast, eight participants finished their training with a targeted PCK for integrated STEM level that included more coherence in terms of integrating STEM disciplines. Similar situations have been reported in the literature; for instance, Vossen et al. (2019) noted that teachers participating in their study were differentiated in terms of connecting research and engineering design within PCK for integrated STEM. In their PCK for socio-scientific issues (SSI), Bayram-Jacobs et al. (2019) stated “considering science content and SSI skills goals equally important is an indicator for strong development of PCK for SSI teaching” (p. 1226). Likewise, we described strong PCK for integrated STEM as putting equal emphasis on at least two STEM disciplines in a lesson plan. Our results showed that the training provided helped the participants realize the features of integrated STEM and the necessity of including both science content and other STEM disciplines (e.g., engineering design) in the lesson plan. It seems it would be easier for PSTs to develop PCK for integrated STEM if the necessary knowledge of integrated STEM, engineering, engineering design, and PCK are addressed iteratively. This conclusion is in line with Bayram-Jacobs et al.'s (2019) results. In their study, when teachers developed the necessary knowledge for SSI, they directed their efforts toward how to include SSI in their classroom and how to implement it in class effectively. Hence, it could be concluded that if teachers conceptualize integrated STEM education with regard to both content and pedagogy, they will be able to implement integrated STEM effectively in their class. Finally, regarding the proposed LESMeR model and the training, although we focused only on SMK of engineering and design process in our case, researchers/teacher educators who might use the model should integrate any SMK that their participant teachers need. That is a modification made in forming the LESMeR model based on the training, which is why it is shown in bold and italic font in the model.

The second main element of the model was experiencing six integrated STEM activities throughout the course. Active participation in the activities in terms of teachers’ professional development is highly beneficial (Desimone, 2009). Taking into consideration the role of such experiences, the PSTs provided both the theory and practice of integrated STEM implementation and had the opportunity to play an active role in their own learning such as researching the solution to a daily-life problem, experiencing the design/redesign process, and experiencing the challenges inherent in these activities. Incidentally, the gap between theory and practice of STEM is narrowed in the participants’ minds. Regarding this point, Grossman (1990) stated that experiencing a class as a student or PST contributed to professional knowledge development. Moreover, PSTs generally tend to imitate their previous experience as learners. Therefore, experiencing integrated STEM activities as learners gives PSTs the opportunity to confront the possible challenges and difficulties of designing the product or finding a solution to a real-life problem. Moreover, they observed how the course instructor implemented integrated STEM activities using different strategies (e.g., inquiry-based STEM). By experiencing such, they started to think like teachers who are aware of learners’ difficulties in STEM, and this shows that they are starting to behave like teachers (Nilsson, 2008a). Hence, it is extremely valuable to enrich PSTs with integrated STEM education and real-life STEM practices from a PCK perspective. In this regard, this study has shed light on the role of experiencing STEM on PSTs’ PCK for STEM development. Finally, although we focused on science- (i.e., chemistry) dominant STEM activities, in future training, researchers/teacher educators may utilize any discipline dominant or content integrated STEM activities that do not have any dominant discipline.

The results of the study also extend to the mentoring literature regarding how to support STEM teachers and they give a valuable perspective on the use of mentoring for STEM teacher training. As Feiman-Nemser (1998) stated, “mentoring that helps novices to learn to teach and develop the skills and dispositions to continue learning in and from their practice” (p. 66). Although mentoring has been reported as being a valuable resource in teacher education studies (e.g., Nilsson and Van Driel, 2010; Hume and Berry, 2013; Mena et al., 2017), how one uses mentoring to enrich PSTs’ STEM planning is somewhat ambiguous. As mentees are learners with different backgrounds and needs, mentors should pay specific attention to “what the novices needed to work on and what kinds of experiences or guidance or resources might be helpful” (Feiman-Nemser, 1998, p. 72). From this perspective, the integrated STEM teacher education literature and our experience enlightened us (i.e., PSTs need to know what integrated STEM and engineering are, how to integrate STEM disciplines, and how to design an integrated STEM lesson with essential features of the STEM approach). Another point that needs to be discussed regarding mentoring is its role in making experts’ tacit knowledge explicit to novices (Mena et al., 2017). The participants’ reflection papers and interview data showed that studying with mentors provided the PSTs with the opportunity to take advantage of mentors’ experience and knowledge of STEM. Although mentoring has been conducted in different ways and via different roles (Feiman-Nemser, 1998; Mena et al., 2017), in the context of this study, rather than directing PSTs in what to do, mentors created a group environment in which PSTs started the conversation freely, discussed the most suitable daily-life problem for STEM activity, possible difficulties that K-12 learners might face during the STEM activity, and determined how to assess or what to assess during and at the end of the STEM lesson plan. During those discussions, mentors asked critical questions about what the PSTs’ ultimate goal with regard to planning the STEM activity was or to what extent the lesson plan matched the curricular objectives’ focus, or to what extent the daily-life problem set was relevant to high school students’ lives and interests. By doing so, mentors helped the PSTs review their steps in planning, analysing them critically and, whenever necessary, providing different views or offers that the PSTs did not otherwise notice or realize. Likewise, in Van Driel et al. (2002), mentoring support enriched the participants’ instructional strategies and learner components of PCK. In addition, we revealed that, due to mentoring, the PSTs showed considerable development in all PCK components, even in assessment and curriculum components that were reported as being the least developed in previous research (Hanuscin and Hian, 2009; Henze et al., 2008). Regarding the mentoring cycle, participants may be provided with more mentoring support in future research. Furthermore, different mentoring opportunities (e.g., e-mentoring) may be used in addition to face-to-face mentoring in later stages of training.

Finally, reflection on their own learning and performance was another component of the model that could foster participants’ PCK for integrated STEM development. Nilsson (2008b) stated that reflection is an “important element for student-teachers in developing expertise in their practice, and is central to them accepting more responsibility for their actions” (p. 1284). Encouraging PSTs to reflect on their own experiences enables them to become aware of their personal views of their own experiences, and further helps shape their understanding. At the beginning of the current study, the PSTs were not knowledgeable in terms of what integrated STEM and PCK are and therefore could not have had any experience in planning or implementing integrated STEM activities. Continuous implementation of the LESMeR model gave the PSTs the chance to review their experiences and enhance their understanding of STEM and PCK for STEM. Moreover, considering the tacit nature of PCK (Loughran et al., 2004), reflecting on situations that are significant to PSTs becomes explicit by reflecting on their own STEM knowledge and PCK for integrated STEM development owing to the sources from which the training is derived. It helped in “making the tacit explicit” (Loughran, 2002, p. 35) and provided PSTs with a better understanding of integrated STEM implementation.

To conclude, “[t]eachers must have the pedagogical content knowledge, or PCK, to help them expand beyond science or mathematics to include defining and delimiting engineering problems, designing solutions, and optimizing designs” (Lau and Multani, 2018, p. 196). Our results suggested that providing long-term training with promising practices augmented PSTs’ for PCK for integrated STEM. Although the results ultimately showed two different PCK for integrated STEM (i.e., PCK B and C), both groups presented development to some extent. As Gunckel et al. (2018) stated, “developing PCK for more rigorous and responsive teaching takes time and may require additional resources.” (p. 1357). This long journey should be supported and enriched through appropriate and valuable practices, namely, collaboration with mentors (Hanuscin and Hian, 2009; Lau and Multani, 2018), engaging in the practices of engineering (NRC, 2012) and STEM activities (Lau and Multani, 2018), and reflection (Nilsson, 2008b; Lau and Multani, 2018).

Implications

In this study, we put PCK and its development for STEM lesson planning at the centre of our LESMeR model, as developed for augmenting PSTs’ STEM knowledge and planning for STEM courses. First, we implemented the model in the PST education program. We believe that it can be easily adapted for professional development (PD) activities. As the literature revealed, in-service teachers have somewhat limited knowledge about engineering as a discipline (Cunningham and Carlsen, 2014), which highlights the importance of providing in-service teachers with knowledge about engineering and engineering design processes. Regarding this point, teacher education programs may offer introduction to engineering and engineering design courses co-operatively with faculty from engineering departments. Moreover, teachers should experience integrated STEM activities and reflect on their experiences. Regarding mentoring support, during PDs, mentoring sessions can be easily provided. Also, after PDs, online mentoring (Mena et al., 2017) can be provided through the use of technology and social media. Furthermore, although we planned to develop PSTs’ PCK for integrated STEM over a 13 week long semester, the model proposed in this study may be used to design STEM teacher education programs that extend to two or more semesters. For instance, the first learning cycle should include an introduction to integrated STEM and to engineering, and to STEM subject matter courses. Then, integrated STEM courses should be provided. Additionally, practice teaching courses may be added to the second cycle. During that cycle, mentoring support could be provided by both the faculty and mentors working at schools. Reflection can always be included throughout the program through its utilization in each and every course provided to PSTs.

Second, in this study, the training was provided in a formal classroom context. However, as Lau and Multani (2018) suggested, teacher training for PCK for integrated STEM development may be provided in other contexts such as museums or summer PDs.

Third, in any future studies, researchers should focus on PCK for integrated STEM development for groups of PSTs from science, technology, engineering, and math education departments (i.e., collective PCK for integrated STEM). By doing so, PSTs with different backgrounds would have a chance to learn from each other how to integrate other STEM disciplines into a lesson. Likewise, mentors with backgrounds from different STEM disciplines should provide mentoring together in future studies.

Finally, although our dominant discipline was chemistry (i.e., science) in this study, the LESMeR model has the potential to help researchers from different science disciplines (e.g., biology) or other STEM disciplines (e.g., mathematics, technology, or engineering) to augment teachers’ PCK for integrated STEM. If different STEM activities where the dominant discipline is different than chemistry are used in the experience cycle and mentors with different background participate in to the training, the model serves for teacher educators of other disciplines.

Limitations of the study

This study is limited to 13 PSTs’ declarative PCK captured over the course of a 13 week semester. Moreover, the course did not include any teaching practice, either in a school or faculty context (i.e., microteaching). Therefore, the study did not include any observational data. Moreover, the participants did not have any classroom teaching experience. We are aware of the importance of teaching in a real classroom context and its contribution to teachers’ practice. However, the literature also states that “classroom exposure is no guarantee of the creation of an expert science teacher” (Kind, 2009, p. 174).

Conflicts of interest

There are no conflicts of interest to declare.

Appendix 1: the details of training provided

Weeks Activity-practice Details
1 Learn Cycle-1: Introducing STEM, Engineering, and engineering design process & Reflection on about what PSTs learn about STEM and engineering An interactive presentation focused on what STEM is, the need for STEM education, what engineering is and how to integrate different disciplines together was made.
2 Experience Cycle-1: STEM Activity: Preventing apples browning: inquiry-based STEM activity & Reflection on the activity PSTs worked in groups and designed a process to prevent apples browning. Each group stated a hypothesis that informs their design process and determined dependent and independent variables. Groups discussed about how to collect data, and how to analyse the data collected. Each group created a time lapse video from the photos to show how successful the design in preventing the browning process. Then, each design was presented by a member of each group to other groups. The best process for preventing this browning was determined through the use of criteria set at the beginning of the lesson.
3 Experience Cycle-2: STEM Activity: make your own thermos: Argumentation-based STEM activity & Reflection on the activity Each of the groups worked on a thermos design based on a claim. Groups discussed about how to collect data, and how to analyse the data collected. They collected the data and prepared a dataset by recording temperature changes in a time span through the use of multimeter's temperature probe. Then, each group drew mathematical graphs for temperature change over time and prepared a poster showing a drawing of their designs. Groups criticized each other's claims, designs, and data collection processes. At the end, a second round of presentations was given as to how the data collected supported or refuted it. The best design was determined by the use of criteria set earlier.
4 Learn Cycle-2: PCK introduction & Mentoring Cycle-1: Analysis of a strong STEM lesson plan on airbag design with mentors & Reflection on the mentoring and what PSTs learn PCK and its components were introduced.
By the use of an existing STEM activity, a CoRe was prepared by mentors before the class. Each group, including 4-5 PSTs and a mentor, examined the STEM CoRe (i.e., lesson plan, the details of the CoRe can be found in the data collection part) prepared regarding PCK components. The strong features of the plan were analysed regarding how they informed PSTs regarding learners’ difficulties and curriculum objectives, STEM instructional strategies, and how to assess learners’ understanding and/or their design throughout, and at the end of, the activity. Additionally, the lesson plan was analysed via the use of a STEM features rubric prepared by the instructor in the light of Moore et al. (2015). The rubric states the integration of STEM and STEM+ into the activity, student centeredness of the activity, existence of daily-life problem, engineering design and re-design processes. Mentors highlighted how to integrate mathematics into the lesson plan (e.g., ‘’Provide mathematical evidence that the amounts of chemicals used in your design are appropriate to meet the requirements and constraints without reactants being wasted.’’) Each group with its mentor discussed about how to integrate mathematics, technology, and engineering into airbag design challenge module.
5 Experience Cycle-3: STEM Activity: Making bouncy polymer: project-based STEM activity & Reflection on the activity PSTs worked in groups and designed a bouncy polymer. The lesson was started with a contest announcement made by a company that is looking for engineers who are able to design bouncy balls. A price list of the materials that PST would use in design process was provided at the beginning of the activity. The best design was determined by the use of criteria set earlier. Moreover, groups recorded slow motion video to measure the bounciness of the balls to win the contest of the company. At the end, a whole group discussion was held as to what extent the ‘Bouncy Polymer’ activity has features of project-based learning.
6 Experience Cycle-4: STEM Activity: Making a rocket: argumentation-based STEM activity & Reflection on the activity Each group worked on a rocket design based on a claim. Groups discussed about how to collect data, and how to analyse the data collected. Then, groups prepared a poster showing a drawing of their design. Groups criticized each other's claims, designs, and data collection processes. At the end, a second round of presentation was given on how the data collected support or refute it. The best design was determined through the use of criteria set earlier. Moreover, after the activity, a group discussion was held on STEM pedagogies (i.e., argumentation-, inquiry-, and project-based STEM activities). The instructor and PSTs compared and contracted each STEM pedagogy by making a chart on the whiteboard.
7 Mentoring Cycle-2: Analysis of a poor STEM lesson plan on making a toothpaste & Reflection on the mentoring and what PSTs learn Through the use of an existing STEM activity, a CoRe was prepared previously by mentors. Each group, including 4–5 PSTs and a mentor, examined the STEM CoRe (i.e., lesson plan) regarding PCK components. The poor aspects of the plan were analysed with regard to PCK components. Additionally, the lesson plan was analysed through the use of a STEM features rubric prepared by the instructor in the light of Moore et al. (2015). Then, the groups worked on the plan to make it stronger. Groups added more familiar daily-life problems and/or challenge to start the activity. Also, groups utilized STEM pedagogies (i.e., two groups preferred to use inquiry and one group preferred argumentation in their plans). Finally, the groups shared their revised lesson plans, which were stronger than the existing ones.
8 Experience Cycle-5: STEM Activity: designing a fire extinguisher: Inquiry-based STEM activity & Reflection on the activity PSTs worked in groups to design a fire extinguisher. Each group designed a hypothesis that informed their design process and determined dependent and independent variables. Groups discussed how to collect data and how to analyse the data collected. Each design was presented by a member of group to other groups. The best design was determined through the use of criteria set earlier.
9 Experience Cycle-6: STEM Activity: design a voltaic cell with highest voltage: inquiry-based STEM activity & Reflection on the activity PSTs worked in groups to design a voltaic cell with the highest voltage. Each group stated a hypothesis that informed their design process and determined dependent and independent variables. Moreover, through the use of the Nernst Equation, which was based on the concept of logarithm in mathematics, they estimated the voltage that they would read. In this activity, how mathematics help engineers in calculating a cell potential beforehand, and how engineers use mathematics in their work were discussed. Groups discussed how to collect data and how to analyse the data collected. Each design was presented by a member of each group to the other groups. The best design was determined through the use of criteria set earlier.
After the activity, a group discussion was held on assessment in STEM education. The instructor asked: “How should we assess in STEM education?” After taking PSTs’ ideas, a presentation was given on how to assess in STEM. Then, a discussion was held on ‘what to assess in STEM’. Likewise, a presentation that included examples of what to assess was provided.
10 Mentoring Cycle-3: Adaptation of a cookbook science activity into STEM activity & Reflection on the mentoring and what PSTs learn Each group with their mentors worked on the adaptation of a cookbook activity into a STEM activity. The original activity was found in a tenth-grade chemistry textbook and was related to colligative properties. In the activity, learners were asked to measure the freezing point of solutions with different concentrations of CuSO4·5H2O.
After adaptation, each group presented their activities. One of them started with a problem that officers in the General Directorate of Highways looked for a green chemical that prevents freezing of water on the highways. The group prepared a price list for the design chemicals and experiments and planned a project-based STEM activity. Another group started the activity with a design challenge regarding a cold pack for the school football team and planned to implement inquiry.
11 Learn Cycle-3: Instructional strategies used for design teaching & Reflection on the new strategies and how to integrate them into STEM lessons Strategies taken from ‘The Informed Design Teaching and Learning Matrix’ published by Crismond and Adams (2012) were presented. During the presentations, strategies were discussed regarding how to use those strategies in previous STEM activities that the PSTs had already experienced (i.e., examining existing fire extinguishers in designing a fire extinguisher activity)
12 Mentoring Cycle-4: A cooperative STEM lesson planning: developing a new STEM lesson plan & Reflection on the mentoring and what PSTs learn Groups were formed (including 4–5 PSTs). Each group worked on a STEM lesson plan in the CoRe format. Then, each group presented their plans regarding a daily-life problem, objectives addressed, possible difficulties that learners’ face during the design process, instructional strategy used, and assessment of the designs and learners’ understanding.
13 Reflection on the contribution of the course A discussion was held on the contribution of the course to PCK for STEM development. PSTs reflected on their development.

Appendix 2: Julie's Post-CoRe

CoRe Lesson Plan
Grade Level: 9th grade Curriculum Objectives
Subject: Interactions between chemical species At the end of this lesson students will be able to;
9.3.1.1. explain what chemical species are.
9.3.2.1. classify interactions between chemical species.
(a) Interactions between species could be classified as interatomic and intermolecular.
(b) Examples of strong interactions include ionic, covalent and metallic bonds; examples of weak interactions are hydrogen bond and van der Waals forces.
develop designing ability to design a water purification system based on Interactions between chemical species (not existed in the curriculum)
  Big Idea 1 Big Idea 2
  Interactions between chemical species are classified and related concepts are taught. Weak interactions, especially van der Waals interaction, is explained.
1. What concepts/big ideas do you intend students to learn? I want them to learn I want them to learn
• what ionic, covalent and metallic bonds are. • how to distinguish weak and strong interactions on the basis of bond energy.
• how to classify interactions between chemical species. • what van der Waals interaction is.
• what strong and weak interactions are. • how to relate the physical properties of matter with hydrogen bond.
• the working principle of water purification system.
2. What do you expect students to understand about this concept and be able to do as a result? I expect them I expect them
• to distinguish the differences among ionic, covalent and metallic bonds. • to distinguish the differences
• to establish a connection between different types of interactions • among dipole–dipole, ion-dipole, ion-induced dipole and London forces.
• to differentiate strong and weak interactions • between physical and chemical changes on the basis of the amount of the energy change.
• to design.
3. Why is it important for students to learn this concept? It is important to It is important
• recognize the type of the bond. • to learn daily life applications of chemistry.
• differentiate the type of the interaction. • for critical thinking.
• develop designing ability  
4. What difficulties do students typically have about each concept? Due to the abundance of the concepts in this topic, students may mix them up easily. They may not be able to imagine the interactions between species.
They may have difficulties in deciding about how to combine the materials to design a water purification system It may be difficult for learners to understand how van der Waals forces arise between impurities and purification system works.
5. What misconceptions do students typically have about each concept? They may think that ionic compounds are often liquid. • HCl is an ionic compound.
They think that electrons are shared in ionic compounds as in the covalent structures. • Nitrogen can form five covalent bonds.
• Covalent bond is the result of electron exchange between two non-metals.
• Non-polar covalent molecules do have charge, polar covalent molecules do not.
• While molecule is the smallest unit of the same type of atoms formed by covalent bonds, compound is the smallest unit of different kinds of atoms with ionic bonds.
6. Which teaching strategy and what specific activities might be useful for helping students develop an understanding of the concept? Explain in detail. Let's Design A Purification System
Problem: You work in a factory that designs water purification systems. The common problem of purification devices, which are used in almost all houses, is filters. (On some devices, filters are changed every two months.)
As the workers of the factory, we want to extend this period and design the best purification system. How do you design it?
Criteria:
The system should be; economic, long-lasting (should be changed at least every 6 months), durable, healthful, manufactured fast etc.
Possible Materials:
Energy drink in blue colour (image file: d0rp00074d-u2.tif), activated carbon (image file: d0rp00074d-u3.tif), glass (image file: d0rp00074d-u4.tif), chronometer (image file: d0rp00074d-u5.tif), filter paper (image file: d0rp00074d-u6.tif), spoon (image file: d0rp00074d-u7.tif), acetate pen (image file: d0rp00074d-u8.tif), plastic bottle (image file: d0rp00074d-u9.tif), knife (image file: d0rp00074d-u10.tif), scotch tape (image file: d0rp00074d-u11.tif), scissors (image file: d0rp00074d-u12.tif), funnel (image file: d0rp00074d-u13.tif), cardboard cups (image file: d0rp00074d-u14.tif), distilled water (image file: d0rp00074d-u15.tif), tap water (image file: d0rp00074d-u16.tif), muddy water (image file: d0rp00074d-u17.tif), juice (image file: d0rp00074d-u18.tif), food colouring (image file: d0rp00074d-u19.tif)
Class is divided into groups of 3 or 4 (heterogeneous groups)
Groups are given 20 minutes for research on existing water purification systems, their components and working principle.
Each group identify their argument. They prepare a poster or presentation to present their arguments to the whole class. Then they made their presentations. In the presentation they explain which material they used and why? Groups can change their arguments before starting the design process if they want. Each group choose the materials they want to use. Then they start to design purification systems regarding their arguments (30 minutes for design process). They test their devices by collecting and analysing data. Based on the findings, students discuss why they have succeeded/failed in their designs and re-design the purification system. The most successful group is announced as the winner.
Teacher may bring a water purification system and investigate the components and working principles of the device with students (reverse engineering).
7. In what ways would you assess students’ understanding or confusion about this concept? • Why is activated carbon used in purification systems?
• Give examples of physical interactions and van der Waals interactions from daily life.
• Prepare a report considering the design steps.
• Write in detail what you want to change and why you want to change them during the re-design phase.
• Fulfil the design log and deliver at the end of the activity.
The system should be; economic, long-lasting (should be changed at least every 6 months), durable, healthful, manufactured fast.
Materials:
Energy drink in blue colour (image file: d0rp00074d-u20.tif), activated carbon (image file: d0rp00074d-u21.tif), glass (image file: d0rp00074d-u22.tif), chronometer (image file: d0rp00074d-u23.tif), filter paper (image file: d0rp00074d-u24.tif), spoon (image file: d0rp00074d-u25.tif), acetate pen (image file: d0rp00074d-u26.tif), plastic bottle (image file: d0rp00074d-u27.tif), knife (image file: d0rp00074d-u28.tif), scotch tape (image file: d0rp00074d-u29.tif), scissors (image file: d0rp00074d-u30.tif), funnel (image file: d0rp00074d-u31.tif), cardboard cups (image file: d0rp00074d-u32.tif), distilled water (image file: d0rp00074d-u33.tif), tap water (image file: d0rp00074d-u34.tif), muddy water (image file: d0rp00074d-u35.tif), juice (image file: d0rp00074d-u36.tif), food colouring (image file: d0rp00074d-u37.tif)
pH strips.
Rubric used for design.
  Wonderful Adequate Inadequate
Economic Necessities about image file: d0rp00074d-u38.tif Necessities about image file: d0rp00074d-u39.tif Necessities more than image file: d0rp00074d-u1.tif
Healthful Limpid water with drinkable pH Limpid water with high/low pH or Blurry water with drinkable pH Blurry water with very high or low pH
Durable Can be used for many times Can be used for two or three times Used only ones

Julie's design log attached to her post-CoRe

What do you think about the materials that can be used in water purification system? Write any ideas come to your mind.
 
What do you want to know about to design a water purification system?
Which materials can be the best for a water purification system?
Which sources will be helpful for you?
Find out what there is to know about this challenge. Write questions that you want to do research.
After the research, if you have learnt something useful, write them down with a different colour pen.
 
Design your water purification system and write the materials used.
Write your argument why your design will be successful.
Talk to the instructor and get her feedback.
 
Design your water purification system.
Before test your design, record data, and assess its effectiveness in regard to the criteria given at the beginning.
Explain how your data collected support your argument.
What can be done to improve your design? Try to write at least one suggestion to improve it, go back to design stage and write it in a different colour.
 
Based on your initial design and revisions made, re-design your water purification system.
Outline the final version of your design
 
Evaluate your design by the use of the criteria stated at the beginning.
Compare and contrast the first draft and the final version of the design. Evaluate your improvement.

Appendix 3

The elective STEM course was the first integrated STEM course for the participants of the study. The PSTs have mostly taken chemistry-specific content courses and pedagogy courses. Hence, what PSTs learned about integrated STEM would be helpful for researchers who plan to replicate the design of our study. We can summarize the participants’ learning under four categories.

(1) They learned what integrated STEM approach is and the essential features of the integrated STEM approach (i.e., daily-life problem, integration of different disciplines, design and re-design, etc.). Through the end of the course, we asked PSTs to analyse their pre-CoRe. In the reflection paper that they wrote, they stated that their pre-CoRes were not a STEM lesson plan. They criticized their own pre-CoRes regarding the lack of essential features of integrated STEM, which is a good sign for the researchers.

(2) The course enriched their PCK and PCK for integrated STEM. The introduction of PCK construct and its components, and then use of PCK language through the semester, focus on the PCK components through mentoring sessions, integrate PCK components to the reflection papers, and use of the CoRe instrument helped PSTs learn the construct in detail.

(3) PSTs came to better understand that chemistry is in our lives. Moreover, they learned that designs of many different tools (i.e., air bag, fire extinguisher, polymers, and thermos) are based on chemistry concepts. They knew some of them in theory but owing to the activities that they participated in actively, they had much richer and detailed knowledge of working principles of those tools and chemistry knowledge used in their design process.

(4) Due to chemistry specific nature of the program that they enrolled to, PSTs did not have opportunities to integrate chemistry content knowledge with other disciplines. However, this course, based on the practices mentioned in LESMeR model, offered a great opportunity for the chemistry PSTs to experience how to integrate chemistry with other disciplines and how to use chemistry in engineering design process. For instance, in Bouncy Polymer design challenge, PSTs observed characteristics of different polymers produced with different glue-borax mass ratios. They collected evidence regarding how the mass ratio results in different characteristics of the polymer produced, which shows them how chemical engineers or material engineers work and use chemistry and mathematics in the design of materials.

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