Critical thinking is the ability to think rationally and reflectively about what must be done or believed. This skill allows one to make logical decisions based on information obtained and processed according to ability. The development of critical thinking skills in learning is essential because they enable students to deal effectively with social, scientific, and practical problems. Therefore, this research aimed to describe the effectivity of problem-based learning to improve students'

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... al thinking skills to deal with hoax information in chemistry. This research was carried out through the control and experimental groups. Data were collected from 60 the 11th-grade students of the State High School in Lampung Province, Indonesia, and analyzed by using SPSS version 23.0. The effectivity of problem-based learning was measured based on the n-gain. The n-gain value of experimental and control classes was 0.709 (high) and 0.322 (medium), respectively. The results indicated that problem-based learning has facilitated and effective to improve students' critical thinking skills.