JPII 9 (1) (2020) 11-21 Jurnal Pendidikan IPA Indonesia http://journal.unnes.ac.id/index.php/jpii ETHNO-STEM PROJECT-BASED LEARNING: ITS IMPACT TO CRITICAL AND CREATIVE THINKING SKILLS W. Sumarni *1 and S. Kadarwati 2 1,2 Dept. of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Negeri Semarang DOI: 10.15294/jpii.v9i1.21754 Accepted: November 5 th 2019. Approved: February 24 th 2020. Published: March 31 st 2020 ABSTRACT Guiding students to think critically and creatively is a crucial part of the educational process to meet the required skills in the 21 st century. Besides, attention to the local culture especially that is closely related to the scientific concepts needs to be strongly emphasized. Due to those two aspects i.e. creative and critical thinking as well as attention to local culture, the ethno-STEM project-based learning for high school students has been implemented and its impact on students’ critical and creative thinking skills has been investigated. This study involved 230 students from seven high schools in Central Java, Indonesia. The data collection was carried out through a set of instruments to reveal the students’ critical and creative thinking skills. The instruments were declared as valid based on the experts’ judgment and showed an Alpha Cronbach score of 0.79 before use. The results showed that the ethno-STEM project-based learning was able to improve the average critical and creative thinking skills of students in all indicators varying from low to medium categories. The improvement of students’ critical thinking skills was observed by the achievement of the N-gain score, i.e. 52 students (22.6%) achieved a high category, 102 students (44.4%) achieved a medium category, and 76 students (33.0%) achieved a low category. Moreover, an increase in the creative thinking skills was also observed, indicated by the N-gain score, i.e. 63 students (27.4%) were at a high category, 109 students (47.4%) were at a medium category, and 58 students (25.2%) were at a low category. In conclusion, the ethno-STEM project-based learning showed a significant effect on the improvement of students’ critical and creative thinking skills. © 2020 Science Education Study Program FMIPA UNNES Semarang Keywords: critical and creative thinking; ethno-STEM; ethno-STEM project-based learning INTRODUCTION Market demands in the 21 st century require employees to have capabilities in critically overco- ming problems and producing creative solutions (Nakano & Wechsler, 2018). At the same time, they must also have a full mastery in sciences, technology, engineering and mathematics (Lilia- wati et al., 2018). Therefore, teaching-learning processes must meet the standard needs of gra- duates in this century by providing students with high-level thinking skills. High-level thinking skills, especially critical and creative thinking skills, are urgently needed in utilizing the students’ knowledge for problem- solving and decision making in various fields of life (Retnawati et al., 2018). Thinking differently and critical thinking are very important for stu- dents to make a decision when they face several options (Fields & Bisschoff, 2014). However, low-level thinking skills were often used in many learning processes at schools (Saido et al., 2015). The students’ critical and creative thinking poten- tial in the classroom’s learning process was not well-developed. The preliminary observations in several high schools in Semarang (Central Java, *Correspondence Address E-mail: worosumarni@mail.unnes.ac.id