The importance of knowledge and technology has increased day by day in the century we live in, and causes many changes and innovations. These developments give rise to an economic development for a country to show a great rise among other countries. In addition to economy, problems or challenges that are met in daily life can be solved with the help of these developments. Accordingly, new generation students should be trained with this consciousness, and earned knowledge and skills to solve their problems that they may meet. The students need to have 21^st century skills (e.g. problem solving, critical thinking, self-management, time management, self-development) and knowledge, and they should integrate them to different situations in their daily life (Nargund-Joshi, Liu, Chowdhary, Grant & Smith, 2013). Thus, educational environment which integrates different disciplines for necessary knowledge, innovation qualifications and 21^st century skills should be designed for the students. Therefore, STEM education supports the interaction among science, technology and engineering.

The word of STEM is abbreviation of first letters of Science, Technology, Engineering and Mathematics. STEM makes a bridge between these four different disciplines, so it is an interdisciplinary area (Meng, Idris & Eu, 2014). Most countries value STEM education, and there are many developments in the field of STEM education. Although Turkish educational system gives the importance for STEM education, unfortunately its application in K-12 schools is weak.

In 2017 Turkish Science Curriculum, engineering design-based objectives was added namely “Science and Engineering Application” as a new unit in each grade level in Turkey to make “engineering (E)” part of STEM education clear (MEB, 2017). In 2018 Turkish Science Curriculum, some objectives about designing or producing a model about a daily life problem as an “Science, Engineering and Entrepreneurship Applications” in each grade level such as desinging illumination tools used in the future (4^th grade level objective), designing an environment supplying sound insulation (6^th grade level objective), designing a model decreasing resistance of water and air (7^th garde level objective) are included (MEB,2018).

There are many studies about STEM education on students’ academic achievement and motivation. According to Yıldırım and Altun (2015), students trained with STEM education are better in learning and academic achievement rather than others not trained with such education. Besides academic achievement of students, there is also positive effect of STEM education on students’ motivation (Şahin, Ayar &Adıguzel, 2014). Moreover, engineering design-based instruction to teach science has potential to increase student interest in science and engineering (NAE & NRC, 2014). Despite these advantages and emphasis of engineering and design skills in 2018 Science Curriculum, engineering part is not emphasized clearly because of ignorance of application of these engineering design-based objectives. In addition, nature of engineering (NOE) research is still at its infancy, and there are limited studies exploring students’ and teachers’ NOE views. Deniz, Yesilyurt, Kaya, and Trabia (2017, April) pointed out that similarity between nature of science (NOS) which is a major research agenda in science education and NOE aspects like tentative, subjective, socially and culturally embedded etc. except engineering design process (EDP). In their study, they adapted NOS research framework for the purpose of assessing elementary teachers’ NOE views. In a similar vein, in the present study students’ NOE views change with engineering design-based instruction were examined by integrating the EDP aspect to NOS aspects. In the study engineering design-based instruction and EDP were emphasized during the “Force and Energy” unit to improve students’ engineering and design skills and NOE views. This study was designed to address the following research question;

• How do 7^th grade students’ nature of engineering (NOE) views change with engineering design-based instruction?

In this study, case study which is type of qualitative research was used because of analyzing 3 different students’ NOE views changes. Researchers can be provided tools to study complex phenomena within their contexts with case studies (Baxter & Jack, 2008). 24 7th grade students in a public school selected conveniently in Ankara were involved in this study. Data were collected from 3 different students by using “Views for Nature of Engineering; Elementary School Version (VNOE-ES)” instrument. These students were selected according to their scores of first science exam; one student assigned as “K” had highest score; one as “L” had middle score; one as “M” had low score depending on average score of the class. VNOE-ES instrument was adapted to Turkish language by the researchers from “Views of Nature of Engineering Elementary School Version (VNOE-E)” developed by Deniz, Yesilyurt, Kaya, and Trabia (2017, April). VNOE-ES covers 11 open ended questions based on NOE aspects namely; demarcation criteria (What is engineering? What makes engineering different from other disciplines?), EDP (steps namely problem determination, searching possible solutions, deciding best solution, designing a model, and testing and improving), tentativeness (not following an order for EDP steps), creativity (engineers’ creativity during EDP), subjectivity (no unique solution for a problem), social aspects of engineering (construction through social negotiation), and social and cultural embeddedness (interaction between engineering and society). The instrument was adminestered to the students as pre and post-test to examine the changes of students’ NOE views. During 12 lesson hours, presentation about NOE and EDP were presented by an engineer, and engineering design-based instruction was administered by the first researcher according to two different lesson plans on “Force and Energy” unit. These two lesson plans were structured depending on 5E Learning Cycle (Engage, Explore, Explain, Elaborate and Evaluate) model. Engineering design-based activities (“Tower Construction” and “Parachute Construction”) were applied in “Elaboration” part of the lesson, and students followed activity sheets depending on EDP steps which was integrated aspect to NOS aspects. Moreover, other NOE aspects were evaluated during EDP steps in the activity sheets. In data analysis, results of three different student views were presented for each NOE aspect seperately. Similar to NOS categorization schema (Bilican, 2014), students’ NOE views were categorized as “informed” (stating developed NOE aspect view including extended examples), “adequate” (stating a developing view but with lack of deep examples), or “inadequate” (stating a misconception or not allinged view).

K’s exam score was 100 point, and K showed improvement in his demarcation aspect, creativity, social and cultural embeddedness, and EDP aspects of NOE over engineering design-based instruction. His responses to these aspects were categorized as “adequate” in pre-VNOE-ES, while they were categorized as “informed” in post-VNOE-ES because of supporting his views with extended examples. For example; in social and cultural embeddedness aspect, “Engineering design solutions make easier our life” in pre, while “We can make easier our works when we have difficulties such as using machines” in post. Therefore, there was an improvement by stating an example. There is no change in his views for other NOE aspects. L’s exam score was 76 point, and L showed improvement in his creativity, social aspects of engineering, social and cultural embeddedness, EDP aspects of NOE over engineering design-based instruction. His responses to creativity, social aspects of engineering, social and cultural embeddedness aspects were categorized as “adequate” in pre-VNOE-ES, while they were categorized as “informed” in post-VNOE-ES because of supporting his views with extended examples. Besides, his response to EDP aspect was “I did not heard engineering design process before”, and categorized as “inadequate” in pre-VNOE-ES, while it was “It means a process about how a design is produced”, and categorized as “informed” in post-VNOE-ES because of changing his idea and supporting his views with extended examples. There is no change in his views for other NOE aspects. M’s exam score was 51 point, and M showed no improvement in his NOE views except subjectivity aspect over engineering design-based instruction. Her response to subjectivity aspect was categorized as “informed” in pre-VNOE-ES, while it was categorized as “adequate” in post-VNOE-ES because of not supporting her view with examples. Therefore, engineering-design based instruction supported the development of students’ NOE view positively.

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