Implementation of Problem-Solving Learning to Improve Critical Thinking Ability of Chemistry Students

English abstract only consisted of one paragraph This class action research aims to describe how to implement the Problem Solving (P.S.) model that can improve chemistry primary students' critical thinking skills (K.B.K.). The research subjects included 36 Chemistry Education study program students taking the Advanced Basic Chemistry course. The main instrument in this study was the researcher, who used observation sheets. There are four phases in this study. Each cycle is planning, implementation, evaluation, and reflection. The steps of problem-solving are determining the problem (by writing down the known data), Designing a solution strategy (by writing down the formula or method used, solving the problem, and reviewing the problem-solving (by asking if the solution is by the concept). These steps improve critical thinking skills, especially in analysing, inferring, deducing, and evaluating.