Physics learning by PhET simulation-assisted using problem based learning (PBL) model to improve students' critical thinking skills in work and energy chapters in MAN 3 Sleman

In the implementation of educational activities in schools there are often challenges that come from within and from outside, one of which demands advances in technology that must be followed by the positive side and left the negative side. The challenges that arise from the development of human life become a separate requirement for a teacher to adapt his learning to existing demands (Davis, 2013). In line with this explanation, Purbasari et al. (2013) stated that technological advances in the world of education are currently developing rapidly with the large use of smartphones by students in learning activities. This is consistent with the data obtained by Agusta and Djukri (2015) that the use of smartphone types of smartphones by students in MAN 3 Sleman, Yogyakarta is 52.35%. However, the use of smartphones by these students has not been able to have a positive impact in achieving the desired learning goals (Manumpil et al., 2015).

Most students abuse the use of smartphones in classroom learning such as just playing games, watching videos, and even exchanging messages with friends or others (Anita, 2013). In line with this, Fatimah and Mufti (2014) stated that students tend not to realize that the use of smartphones in learning activities can also facilitate them in understanding chapter taught by teachers, one of them through various android-based learning applications. Furthermore, Astra et al. (2015) and Dwijananti and Hadi (2016) stated that learning medium in the form of physics laboratories and physics comics based on android are suitable for learning medium for high school students. Wardani et al. (2017) also proved that android-based physics games can improve student learning outcomes and critical thinking skills.

However, technological advances in education must also be integrated into the current physics subject curriculum, especially in Indonesia, i.e the 2013 Curriculum. In the 2013 curriculum, learning material is explaned to students using a scientific approach, where students are trained to observe problems, analyze, solve, and communicate them in writing and orally with the assisted of existing technology (Hosnan, 2014: 34). In addition, students are also required to be skilled in various things, such as reasoning, processing, and presenting data or solutions to problems that are critical, creative, effective, collaborative, communicative, and solutive (Minister of Education of the Indonesia Republic No. 21 of 2016). Physics has an important role in advancing education in Indonesia, thus attracting educators to carry out physics education in a planned manner based on existing physics concepts that are integrated with phenomena or events that occur in the surrounding life. However, in the implementation of physics education in schools it would be better, if the physics chapter taught by the teacher to students is packaged using practical technological assistance and connecting physics chapter with phenomena in everyday life (Suastra et al., 2017). In line with this finding, Luangrath et al. (2011) found that the results of assessment of students' conceptual understanding and critical thinking in the mechanics chapter combined with events or experiences from daily life were higher than textually.

Physics learning with the assisted of technology and applying it to phenomena in daily life will be better if it is adjusted to the learning guidelines or curriculum in schools, one of the 2013 Curriculum (Kuswandari, 2013). Learning in the 2013 Curriculum uses a student-centered learning approach, where students are asked to find out information independently and the teacher is only a facilitator (Megawarni, 2015). Therefore, in this revised 2013 curriculum, it is recommended that learning models used in learning activities are inquiry models, project-based learning models, and problem-based learning models because they are in accordance with scientific approaches and train students' critical thinking skills (Shoimin, 2014). Learning resources used by students in physics learning activities do not only come from the teacher, but can be from anywhere related to physics chapter. With the variety of learning resources used by students in learning a physics chapter, students are expected to be able to understand physics chapter and be able to find problems with solution solutions related to physics chapter in everyday life (Suwandi et al., 2016). Problems related to physics in daily life must have multidimensional answers, so that they can be solved in various ways (Rudyanto, 2014).

Meanwhile, through observation activities at school found problems such as the lack of innovative learning medium used by teachers in explaning physics chapter to students, so students are not enthusiastic about the material explaned by the teacher. Teachers are only fixated on using learning medium that is only provided by schools, they do not collaborate with students to develop their own simple physics learning medium in accordance with technological advancements (Chai et al., 2017; DeFauw, 2018). In addition, another problem found in learning physics at school is the tendency of teachers to explanation physics learning materials just being centered on the teacher. One reason that is often expressed by teachers is why they often use the discourse method to explanation physics chapter to students, because they think the discourse method can accelerate the explanation of physics chapter to students rather than other methods or models that are student-centered (Moradi et al., 2018). Therefore, the impact that often occurs in students with physics learning methods like that is a variety of important abilities that must be mastered by students can not be mastered optimally, such as the ability to understand concepts, critical thinking skills, and creative thinking abilities (Lince, 2016). In addition, students also cannot optimize their confidence, curiosity, and communication skills in public if physics learning activities still use teacher-centered methods (Sari et al., 2019).

Actually, there have been many physics learning medium that have used technology, both in the form of an android simulation medium (PhET), physics learning videos, or online physics comics. However, from a variety of physics learning medium that applies the easiest and cheapest use of the technology to be used in high schools in Indonesia by teachers and also students is to use an Android-based simulation medium such as PhET (Yusuf, & Widyaningsih, 2019). The reason is very logical because more than 52.35% of students use smartphones and of course teachers must also have used smartphones too (Nagel, 2018). In addition, the PhET simulation is a physics learning simulation medium that has been provided by developers on the internet and we just simply download and use it on a smartphone or laptop in accordance with the physics chapter that we are going to study (Nurahman et al., 2019). This medium is offline or does not use internet signals in its use, so this medium is very cheap and easy and can be used anywhere and anytime. With the PhET simulation in learning physics, students can learn physics independently and actively centered on themselves and the teacher only as a facilitator (Bo et al., 2018). This PhET simulation also supports student-centered physics learning activities carried out by the discussion method with various learning models that require active students (Roll et al., 2018).

Meanwhile, there have been many physics learning that uses a variety of methods and models that are student-centered, one of which is the question-and-answer discussion method with PBL models. The problem based learning (PBL) model is one of the student-centered learning models, by combining problems that occur in everyday life with physics concepts and students are asked to solve these problems with critical thinking (Wijnia et al., 2019). The application of PBL models in physics learning will be more optimal, if physics problems can be integrated with instructional medium that students can directly use either individually or in groups (Darma et al., 2018). Therefore, one of the learning medium that supports the PBL model is the PhET simulation medium, because this medium can be used directly by each student in the group to assist find solutions to solving everyday problems with the concept of physics (Umarella et al., 2019).

Meanwhile, Hayati et al. (2013) suggested that the teaching-learning process that uses the PBL model can familiarize students in implementing the scientific method by providing students with independent opportunities to improve their critical thinking. Students who use the PBL model in their learning activities, then in their learning activities are much better because they actively participate in learning activities (Siwa & Muderawan, 2013). Furthermore, Astutik and Prahani (2018) states that learning physics assisted with android simulations can improve students' creative and critical thinking skills. Moreover, physics learning especially in chapter related to mechanics, is combined with PhET simulations and PBL models, students will be more active in learning and their critical and creative thinking skills will increase. Furthermore, Sugiarto and Djukri (2015) argues that PBL model with android simulation is able to assist in increasing students' critical thinking in overcoming environmental problems. As is done by Czabanowska et al. (2012), that the implementation of learning activities that use PBL learning model can develop students' thinking skills through information processing, critical thinking, and instill in the students themselves to be responsible. Meanwhile, Tan (2014) also mentioned that PBL has been recognized as a development of active learning centered on students, using unstructured problems (real-world problems or everyday life) as a basis in the learning process.

Meanwhile, the physics chapter used in this chapter is physics in the scope of mechanics, i.e work and energy. This chapter is adapted to the results of research which states that work and energy is one of the chapter in physics that is misconceptions still occur and is one of the physics chapters that is not easy (Kubsch et al., 2017). In addition, the concept of work and energy is included in the concept whose phenomenon tends to be abstract because this concept cannot be observed with the naked eye (Zhang et al., 2019). Meanwhile, a study was conducted by Ivowi who examined misconceptions in physics from 128 students from two high schools in Nigeria (Graham & Berry, 1996). He asked students to explain clearly about energy conservation and about half of the sample gave incorrect answers to energy conservation questions (Graham & Berry, 1996). In the study, Ivowi revealed that (although the concept of energy is related to mass and speed) students associate energy conservation erroneously only with the concept of speed.

Furthermore, Singh and Rosengrant investigated students' understanding of the concepts of energy and work, obtained the result that most students had difficulty interpreting conceptually the basic principles relating to energy and work (Singh & Rosengrant, 2003). In addition, the taking of this material is also adapted to the syntax in the PBL model, so that this is expected to occur during the learning process. Thus, the objectives to be achieved in this study are to produce a PhET simulation-based learning device that is being used in physics learning activities by using Problem Based Learning (PBL) models, knowing the effectiveness of learning medium in the form of PhET simulation in physics learning activity using PBL models, and knowing the improvement of critical thinking skills of students in MAN 3 Sleman. In addition, the existence of this research is expected to be a reference and guide to physics research in future studies.