How to Cite Payadnya, I. P. A. A., & Atmaja, I. M. D. (2020). Implementing “what -if” learning strategy to improve high order thinking skills (HOTS) of students in statistics method I subject. International Journal of Physics & Mathematics, 3(1), 6-12. https://doi.org/10.31295/ijpm.v3n1.115 ISSN 2632-9417 Received August 18, 2019/Accepted November 30, 2019/Published January 01, 2020 6 Implementing “What-If” Learning Strategy to Improve High Order Thinking Skills (HOTS) of Students in Statistics Method I Subject I Putu Ade Andre Payadnya Universitas Mahasaraswati Denpasar, Denpasar, Indonesia Corresponding author email: adeandre@unmas.ac.id I Made Dharma Atmaja Universitas Mahasaraswati Denpasar, Denpasar, Indonesia Email: dharma.atmaja07@unmas.ac.id Abstract---This study aimed to improve students’ high order thinking skills (HOTS) specifically in Statistics Method I subject by implementing the "what-if" learning strategy. This research is a two-cycle classroom action research. The subjects of this study were as many as 16 students in the 2018/2019 academic year as semester IIA students from the Mathematics Education Study Program, Faculty of Teacher Training and Education, Universitas Mahasaraswati Denpasar. Techniques for collecting data used interviews, observations, and essay tests. This research used two methods for data analysis, i.e. qualitative analysis and quantitative analysis. Qualitative analysis uses methods such as mathematical models and analyses that are performed by conducting explanations restricted to data management techniques. Moreover, the quantitative analysis used a simple level calculation to determine the average value and completeness level of students’ high order thinking skills. The study results showed an increase in the students’ high order thinking skills from the first cycle to the second cycle. The average score of the students’ high order thinking skills only exceeded 71.125 with completeness level 62.5 percent in the first cycle. In the second cycle, the average score of students' high order thinking skills is 84,125 with completeness level touching 87.5 percent. The increase in average score from the first cycle to the second cycle is 18,27% and the increase in students’ completeness level is 40%. This study concluded that applying the "what-if" learning strategy in the Statistics Method I subject could improve the high order thinking skills of students. Keywords---"what-if" learning strategies, high order thinking skills, mathematical, models, statistics method I. Introduction 21st-century mathematics learning emphasizes the importance of developing four abilities that include creativity, critical thinking ability, collaboration, and communication skills (Yustinaningrum, 2019). These abilities must be integrated and implemented in mathematics learning in schools. A teacher as an intermediary for delivering information to students certainly has an important role in making it successful (Purbaningrum, 2017). The teacher acts as a facilitator who facilitates students and creates a student-centered learning activity. According to Badjeber & Fatimah (2018), mathematics is a science that aims to train students to think critically, systematically, logically, analytically, and creatively as well as having effective willpower. The ability to think critically, logically, reflective, metacognitive and creative is a higher-order thinking skill or Higher Order Thinking Skills (King et al., 2012). High Order Thinking Skills is a process of thinking of students in a higher cognitive level that is developed from various concepts and methods of cognitive and learning taxonomies such as the method of problem-solving, bloom taxonomy, and the taxonomy of learning, teaching, and assessment (Saputra, 2016; Tumbaco et al., 2019). These high order thinking skills include problem-solving skills, creative thinking skills, critical thinking, argumentative abilities, and decision-making abilities. The main purpose of high order thinking skills is how to improve students' thinking skills at a higher level, especially those related to the ability to think