Nita Andriani Safitri, Saepudin Rahmatullah, Yudi Dirgantara, Ida Farida

This study is based on the importance of students developing skills to solve daily life problems related to dirty water purification. Through case-based reasoning, students solve problems by applying basic chemical concepts. The application of case base reasoning is performed using one shot case study design. The subjects were 37 students of high school in Bandung. The learning objectives of problem solving skill developed include identifying and formulating problems, collecting data, formulating hypotheses, testing hypotheses, conducting experiments and drawing conclusions. The students’ problem-solving skill data were obtained from performance tasks, assessment rubrics and test. The result showed that the four stages of learning (retrieve, reuse, revise, and retain) can be done well to develop problem solving skill and overall students can develop problem solving skill with good category.