From past to present time, research showed that learners can have more relevant, less fragmented, and more stimulating experiences thanks to interdisciplinary or integrated curriculum (Frykholm & Glasson, 2005; Furner & Kumar, 2007; Jacobs, 1989; Koirala & Bowman, 2003). The ‘separate subject approach’ to knowledge and skills in schools can cause that students have difficulty in solving problems because they do not grasp the context in which the problems are embedded (Frykholm & Glasson, 2005). Interdisciplinary or integrated approaches prepare students as well-qualified for both daily and professional life by improving their different skills like critical thinking, problem solving, communication and collaboration etc. Since it is considered that there are many different benefits of using interdisciplinary or integrated education, STEM education (based on the integration of the science, technology, engineering and mathematics disciplines) has been discussed a lot in the recent times. The present century requires that individuals have 21st century skills for the adaptation to the developments all over the world.The STEM experiences provide for strengthening 21st century career and technical skills (Beers, 2011; U.S. Department of Education, Office of Innovation and Improvement, 2016). At this point, STEM education has gained more critical and important role in this age. 21st century skills refer to a set of abilities that people need to develop in order to succeed in the information and technology age. The Partnership for 21st Century Skills (2009) listed the 21st century skills as three types: ‘Information, Media and Technology Skills’, ‘Life and Career Skills’ and ‘Learning and Innovation Skills’ (OECD, 2008). Critical thinking is one of 21st century skills under the ‘Learning and Innovation Skills’ type and defined as “thinking that has a purpose (proving a point, interpreting what something means, solving a problem)” (Facione, 2015, p. 4). In order to succeed about solving problems and making decisions by forming reasonable judgments, critical thinking skills are required in both daily and professional life. According to Volmert et al. (2013, p. 14), critical thinking skills are “vital for learning subjects, carrying out everyday activities, securing and succeeding in a job and participating in and contributing to civic life”. STEM education develops higher level critical thinking skills through an interdisciplinary approach (U.S. Department of Education, Office of Innovation and Improvement, 2016; Volmert et al., 2013). Since the STEM Education includes more problem- and inquiry-based learning, students have the opportunities to build valuable skills in problem-solving and critical thinking. While making STEM practices, it is focused on solving the real-life problems by using critical thinking skills. Therefore, it is especially focused on critical thinking dispositions in this research and it is aimed to contribute to the current literature by using STEM Education to develop pre-service science teachers’ (PSTs’) critical thinking dispositions. In this manner, the research question of current research: Is there a statistically significant effect of STEM education on pre-service science teachers’ (PSTs’) critical thinking dispositions? 

This research was designed as a single-group pre- and post-test model. In this model, a single group is measured or observed not only after exposure to some sort of process but also it is also measured or observed previously (Fraenkel, Wallen & Hyun, 2012). In this direction, the current research was carried out with 20 female PSTs who studied at a public university in Turkey during "STEM education" course. At the beginning of course, “California Critical Thinking Disposition Inventory (CCTDI)”, developed by Facione, Facione and Giancarlo (1998), was applied to PSTs as a pre-test to determine their critical thinking dispositions. In the 1st week, general information about definition of STEM education, its history and importance were given by instructor. STEM Practices started as from 2nd week. The practice process was conducted in the context of "Mechanic and Static" subject. During 4 weeks, PSTs made different STEM practices collaboratively in groups consisting of 5 students by using their science, technology, engineering and mathematics knowledge and skills. They followed the 9 steps of engineering design process (1.identifying need or problem, 2. research need or problem, 3. developing possible solutions, 4. selecting best possible solution, 5. constructing a prototype, 6. testing and evaluating solution, 7. communicating the solution, 8. redesigning and 9. completing decision) (Hynes et al., 2011). During STEM practices, PSTs considered on how they can make these practices and discussed logical reasoning of the prototypes that they constructed with their group mates. In the 2nd week, PSTs tried to construct space vehicle which able to descend on Mars planet without being damaged by using different materials pipette, plastic bag, string, band and paper. In the 3rd week, PSTs made STEM practice by constructing ‘Spacecraft Milo’. This spacecraft should be capable of moving on inclined surface of planets’ land without falling from surface, having a sensor to perceive foreign objects in front of it, and exploring on planets. In the 4th week, PSTs constructed the prototypes of earthquake resistant building by testing the effect of balanced and unbalanced forces on objects’ movements. In the 5th week, teacher candidates made STEM practice by designing a swing bridge prototype. After 5 weeks, “California Critical Thinking Disposition Inventory (CCTDI)” was applied to PSTs as a post-test this time. In data analysis, since the difference scores of pre- and post-test scores showed normal distribution, a paired-samples t-test was used to compare PSTs’ critical thinking dispositions.

In present research, the effect of STEM Education on PSTs’ critical thinking dispositions were examined. Results showed that there was a statistically significant difference between pre- and post-test scores in favor of both PSTs’ post total test scores (t (19) = -6.634, p<.05) and post sub-dimensions test scores: Analyticity (t (19) = -2.527, p<.05), Open-mindedness (t (19) = -3.329, p<.05), Inquisitiveness (t (19) = -2.894, p<.05), Self-confidence (t (19) = -2.339, p<.05), Truth-seeking (t (19) = -2.471, p<.05), and Systematicity (t (19) = -3.871, p<.05). In other words, PSTs’ critical thinking dispositions improved with STEM practices. Similar to results of current study, Soros et al. (2018) in their research found that 10th grade students’ post-test scores about critical thinking were higher than their pre-test scores after using STEM Education plan. NSTA (2018) stated that as an important component of 21st century, it is given to priority to the critical thinking skills in recent years because both educators and employers has become conscious about the importance of critical thinking rather than memorization. In today’s world, acquiring knowledge or skills is not only expected outcome of science education. Individuals should be able to put their knowledge or skills into practice and integrate them with daily or professional life. This can happen with the promoting of critical thinking. However, promoting individuals’ critical thinking skills are not easy task to achieve. STEM Education develops critical thinking skills by giving opportunity to students for tackling real-world problems through hands-on activities (NSTA, 2018). Therefore,the current research is important in terms of presenting a STEM-based approach to develop critical thinking dispositions of PSTs, future science teachers having a crucial responsibility for enhancing their students’ different skills including critical thinking.

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