Impacts of method courses on Vietnamese pre-service teachers’ perceptions and practices: From the perspectives of model and modeling in STEM education

Modeling in visual representations is essential in STEM education because of its concretization in science, technology, engineering, and math learning activities. Therefore, model-based teaching needs to be improved for pre-service teachers (PSTs) to implement STEM education successfully. We conduct the model-based integrated inquiry STEM (MII-STEM) method courses for 16 PSTs in Physics Education in Vietnam. A qualitative analysis was utilized to examine how and to what extent PSTs change in perceptions of models and STEM education. The findings showed that the number of PSTs with a higher understanding of the model increased. PSTs gain a deeper understanding of STEM education and could transfer alternative perceptions of STEM education into STEM lesson plans. PSTs clarified and embedded Science and Engineering Practices in STEM lesson plans. There were changes of PSTs’ STEM lesson plan after the MII-STEM course: (1) product-oriented to process-oriented; (2) make Engineering more apparent; (3) focusing on developing students’ science and engineering practices; (4) define how STEM sub-fields integrated into STEM lesson plans; and (5) using model and modeling in STEM activities. In addition, PSTs had a positive view of the effectiveness of the STEM-focus method course.


Introduction
1.1.STEM integration STEM education refers to education that includes two or more of the STEM disciplines.According to authors [1], "STEM education is an interdisciplinary approach to learning where rigorous academic concepts are coupled with real-world lessons as students apply science, technology, engineering, and mathematics in contexts that make connections between school, community, work, and the global enterprise enabling the development of STEM literacy and with it the ability to compete in the new economy" [1].[2] describes integrated STEM education as "Approaches that explore teaching and learning between/among any two or more of the STEM subject areas, and/or between a STEM subject and one or more other school subjects" [2].Integrative STEM education refers to technological/engineering design-based learning approaches that intentionally integrate the concepts and practices of science and mathematics education with the concepts and practices of technology and engineering education.

Pre-service Teachers' challenges and needs for STEM implementation
With the constant development of STEM education, one of the ongoing challenges to pre-service science teachers (PST) is to help them to develop STEM teaching practice, which is also a core of pedagogical content knowledge (PCK) [3].Science teachers' PCK understanding plays a crucial role in transforming integrated STEM content knowledge into appropriate and effective instruction for different grade levels [4].Teacher comprehension of integrated STEM content and pedagogical knowledge is in-depth essential for PST towards a practical STEM lesson.Without a doubt, it is one of the significant concerns to develop appropriate strategies for the PST training program in STEM education due to its integrated feature [5].Besides, modeling might be considered a scientific practice that increasingly involves digital computation, simulation, and mathematics to understand macro and micro-level scientific phenomena.Modeling is an authentic practice in science, technology, engineering, and mathematics education, which is suitable for implementing STEM education.Hence, modeling should be a fundamental component in science teachers' STEM literacy [6].In this sense, modeling-based teaching might be an appropriate approach for PST to adapt STEM education in school.Nevertheless, few studies focus on model and modeling in integrated STEM education [7].

Modeling-based teaching in STEM education
As suggested in [8], models will be considered representations of unobservable or observable phenomena that depict a set of assumptions and relationships.Model-based learning is a theory that presupposes that we can learn from building, critiquing, and changing our mental models of how the world works [8].Modeling in visual representations is essential in STEM education because of its concretization in science, technology, engineering, and math learning activities [7].Modeling activity in STEM teaching and learning can serve as a meaningful teaching strategy toward authentic problems.The modeling process in STEM education requires learners in transition between fields of study while engaging in science, math, and engineering design-practice activities.Accordingly, STEM disciplines become bound by a closely interrelated relationship [9].Modeling-based inquiry teaching supports PST in teaching contemporary science education, reflecting greater interdisciplinarity and emphasizing the nature of modeling beyond traditional science teacher education courses.With the development of STEM education, an ongoing challenge to pre-service science teachers (PST) is developing STEM teaching practice.Therefore, developing appropriate strategies for PST training programs in STEM education is a significant concern.Nevertheless, few studies focus on model and modeling in integrated STEM education [7].Presently, Vietnam is undergoing a critical nationwide education reform in which STEM education is emphasized as an essential factor.However, there is no specific or separate syllabus for STEM education in the new curriculum.In such a situation, the science classroom is one of the most appropriate environments for integrating STEM into school programs [11].In this sense, the PST training program is a valuable means to contribute to the teacher resource in STEM implementation for the new curriculum.Therefore, this study aims to answer the following questions.
• How is pre-service teachers' performance in model-based method courses?
• How are pre-service teachers' feedbacks about the model-based method course?

Research context
We developed the method course, namely the MII-STEM course, that strengthens modeling-based inquiry and integration of STEM education.We desired to prepare for the next generation of science teachers for science teaching toward STEM education well.The MII-STEM course was designed internationally collaboratively in 2020.Then science educators implemented the MII-STEM course in Indonesia, Thailand, and Vietnam.This current study presented PSTs' performance and feedback in MII-STEM course implementation in Vietnam.

Procedures
We implemented the MII-STEM course from January to April 2020 for 16 pre-service Physics teachers.Most of PSTs (62.5%) were second-year students.The rest of the PSTs were first-year and third-year students.There were ten classes of 120 to 155 minutes of 6 lessons.We collected PSTs' journals to examine their performance and used videotape classrooms for triangulation analysis.Qualitative analysis was utilized to address research questions.

Pre-service Teachers' perceptions of models
PSTs responded to the open-ended question, "In your opinion, what is a model?Please give at least three examples" before and after the MII-STEM method course.The coding scheme development followed the ideas of [12] about the evaluation of the understanding of models.There were three levels of understanding of models.Models were perceived as simply copies of reality "toy models"; " car models"; "miniature urban area model"; "Models are small copies of a building, vehicle, machine, etc" Level 2 PSTs realize a specific, explicit purpose that mediates the model's construction "…which help us better understand the real one's system"; "Model is matter to describe matter, a real phenomenon to specialize essence, the shape of the object, help everyone imagine it easily" Level 3 Level 3 was characterized by three main factors: the purpose of models, instructing of models, and informing capacity "Model is an object which has the same shape as the original object but has reduced it much, simulating the structure and operation of another object for presentation and research." Vietnamese PSTs had a medium understanding of models.Figure 1 illustrates the percentage of PSTs in each level of understanding of the model.PSTs mainly showed an understanding of models at level 2 (more than 50%).In comparison, there was a decrease from level 1 in the pre-test (27.27%) to posttest (12.5%), and PSTs' understanding of the model in levels 2 and 3 increased.The results affirmed that the MII-STEM course enhanced PSTs' understanding of models.Before the MII-STEM course, PSTs perceived models as simply copies of reality such as car models, house models, and molecular models.Also, most of the PSTs mentioned specific purposes of the model such as "…to easily imagine"; "…to present"; and "…to research".Some PSTs realized that different models of the same thing show literally different aspects of real things after the method course.All of PSTs' examples for "models" are physical models in the pre-test.However, some of the PSTs mentioned the mental model in the post-test.A mental model is a form of knowledge organization such as infections, illness, and social mobility [8].When teachers successfully enriched students' mental models Apr 16 th 120 Lesson 6: Practice Evaluate and suggest to improve Mii-STEM lesson plan and the Mii-STEM teaching performance.
means teachers successfully engage students in the inquiry process [8].That is why PSTs should understand mental models before graduation.The result showed positive changes in the PSTs' perceptions of the model.

Pre-service Teachers' perceptions of STEM education
PSTs came to class with particular views about STEM education and demonstrated many ways to express STEM education (Figure 2).STEM education has been implemented in Vietnam for about six years, but there has not had a national STEM curriculum yet [11].Therefore, perceptions of STEM education might be diverse.PSTs' perceptions of STEM education cover all four areas of S, T, E, and M. It is supposed the reason why pre-service teachers are concerned about implementing all four fields in one STEM lesson.Some models show the four areas that play similar roles and have no relationship.Besides, several models clearly show each relationship between fields, even giving views of the order of arrangement for fields.After the course, PSTs perceived STEM education in all STEM sub-fields apparent and relationships among STEM sub-fields.

Figure 2. PSTs' interpretations of relationships of STEM sub-fields in STEM education
Vietnamese PSTs well-designed STEM activities containing STEM characteristics, such as relating to real-world problem-solving and engineering design process [13], [14], even before the MII-STEM course.However, most PSTs concerned about the range of integration of STEM sub-fields and followed the product-oriented teaching process.There were changes to PSTs' STEM lesson plan after the MII-  5) using model and modeling in STEM activities.PSTs adapted the effective instructional models in STEM education such as T-GEM [8] and 6E [15].The engineering design process was more apparent when PSTs intended for students' learning process.Also, two SEPs [16], namely using math and computational thinking (SEP5) and Constructing explanations (for science) and designing solutions (for engineering) (SEP6), were frequently focused on in PSTs' lesson plans.PSTs could point out how S, T, E, and M are integrated into lesson plans.For example, in the STEM lesson plan for "Anti-thief laser device", PSTs clarified knowledge in all STEM sub-fields (Figure 3).Also, PSTs pointed out the STEM education model in a lesson plan, in which Science (S) is considered the home with separate rooms of T-E-M that are used as needed [17] (Figure 4).

Pre-service Teachers' feedback on MII-STEM course
PSTs showed positive views on the MII-STEM course by acquiring "new" things such as a general understanding of STEM education, STEM lesson plans, SEPs, modeling, and instructional models (T-GEM, 5E, 6E, MII).Also, PSTs thought they changed perceptions in STEM education.One PST mentioned, "Previously, I thought STEM education aims to create a usable or practical model.Now I have better understood STEM education".Another PST shared, "STEM education brought the authentic meaning for lessons."However, PSTs still concerned with distinguishing T-GEM, 5E, 6E, and MII and other teaching methods.PSTs sometimes felt challenging to create excellent and explicit tasks when designing a lesson plan and developing assessment tools in STEM education.

4.
Discussions and conclusion Modeling and modeling play an important role in effective STEM implementation.This current study showed positive changes in PSTs' understanding of modeling and modeling.PSTs perceived more comprehensively in all aspects of the model.However, since most of the participants are students in Physics education, the models that students understand, perceive and apply in the teaching process are all physical models rather than mental models.The STEM activities that PSTs designed were also mostly productions.PSTs perceived the mathematical model as a mental model without a more complete view of the mental model such as other mental models in Chemistry education.The mental model in STEM education is a knowledge organization in which learners think, interact, and reason with authentic problems in order to solve practical problems.Many positive changes in PSTs' designing of STEM activities including using models and modeling in STEM activities.Modeling activities include exploratory, expressive, inquiry, evaluative, and cyclic modeling depending on the purpose of learning activities [18], [19].Researchers [20] proposed modelbased inquiry as an effective teaching method in STEM education, specifically in virtual Physics labs.There were six main learning modules designed, namely (1) topic introduction, (2) hands-on experiment, (3) virtual experiment, (4) teamwork, (5) actual applications, and (6) model adjustments [20].Still,  The effectiveness of STEM education on students' competencies has been proved in many studies worldwide [14].Vietnamese educators might strengthen the quality of higher education to prepare for the next generation of science teachers in effective STEM implementation.Model-based teaching involves teachers working with students to co-construct and evaluate students' expressed models [8], which shares some things of STEM education.Therefore, integrating model-based teaching is also a significant concern to improve PST in both model-based teaching and STEM education implementation.
The MII-STEM course contributed to such a purpose in higher education.The progress in students' understanding of modeling and STEM education has shown the relevance and effectiveness of integrating modeling-based teaching in STEM education.This current study affirmed the effects of the MII-STEM course on PSTs' perceptions and practices in STEM education.The embedding of modeling-based inquiry and integration in the method course as a framework for future research in higher education in Asian countries.

Figure 1 .
Figure 1.The percentage of PSTs' understanding about models following three levels

Figure 3 .
Figure 3. Anti-thief laser device Figure 4.The integration of S-T-E-M

Figure 5 .
Figure 5. Modeling phases in teaching

Table 1
describes the specific date, time, lesson title, and overview.

Table 1 .
The overview of the MII-STEM course2.3.Data collection and analytical strategyPre-test and post-test were conducted to analyze PSTs' perceptions of models.The agreement percentage between the first two authors in the coding scheme was 82%.Besides, we asked PSTs to design STEM learning activities to show their perceptions of STEM education.After the course, we interviewed semi-structured with open-ended questions to collect PSTs' feedback.The rest of the disagreement coding was discussed to explicit the coding list.Microsoft Excel 2016 was utilized to gather all data.

Table 2 .
Table 2 presents our coding scheme of three levels of understanding of models and the PSTs' responses as examples.Coding scheme for the understanding of models