Problem solving is an important goal in almost all physics classes. In this study we explore students' perceptions and understanding of the purpose of two different problem solving approaches. In Phase I of the study, introductory algebra-based physics students were given an online extra credit problem-solving assignment. They were randomly assigned one of three problem-solving strategies: questioning, structure mapping and traditional problem solving. In Phase II of the study, eight student volunteers were individually assigned to work problems using one of the strategies in two sessions of semi-structured interviews. The first session investigated students' general problem solving approaches a few weeks after they had completed the online extra credit assignment. The second session investigated students' perceptions of problem solving strategies and how they relate to the extra credit assignments. In this article, we describe students' perceptions of the purpose of the activities and their underlying problem solving techniques.