The purpose of this study was to find out more effective teaching among problem solving strategy with a scientific approach to students' mathematical abilities in high order thinking skills. This quasi experimental study used non-equivalent pretest-posttest control group design. The experimental group was students who were taught with problem solving strategy, and the control group was students who were taught with the scientific approach. The number of participants for the experimental group, n = 138, and for the control group, n = 139 from the 10th grade of public and private high schools in Medan-Indonesia. Based on the hypothesis testing of the study, the results showed that learning through problem solving strategy was more effective than the scientific approach to students' mathematical abilities in communication, creativity, problem solving, and mathematical reasoning.