This study describes and contrasts theoretically and empirically problem solving of situated problems in school and the real world at the macro level as a social-cultural activity system and analyzes the process of solving situated problems by high school students at the micro level as an activity. Three potentially experiential problem tasks were given to 31 last year high School science students. Action map, a concept derived from activity theory, was used to represent the solutions. Qualitative methods were used to analyze the data obtained from the written solutions as well as interviews with the participants. Leont'ev's activity theory and Engestrom's activity system were used as frameworks to analyze and interpret the data. The results indicate that there are fundamental identifiable differences among the activities and the activity systems of problem solving in the real world, situated, and school contexts.