The purpose of the present study was to examine the effectiveness of a strategic training program for improving students' performance in solving multiplication problems. The participants were 3 third graders with math difficulties. In this teaching experiment, microgenetic analysis was used to analyze improvement in students' strategic development and problem-solving accuracy. The instructional components included selective task assignment and OFSD (encouraging students to use "O"wn strategy to solve problems, providing "F"eedback, asking for students' "S"elf-explanations, and explicit "D"emonstration of strategies when needed). The results showed that the three participants began the intervention at different strategic developmental levels and consequently were given differentiated tasks to promote their strategic development during the intervention. In response to the intervention, the three participants improved their problem-solving accuracy, use of advanced strategies, and flexibility in choosing backup strategies.