The purpose of this study was to explore the effects of information technology and inquiring teaching strategy on problem solving performance of quantitative relation unit for an elementary student with learning difficulties in math. The quantitative relation teaching contained the "Intuition" level of the foundation, the "recurrence" level of the common quantity pattern, and the "modelization" of the generalized symbols. The study was conducted by the "multiple probe design across behaviors" in the single subject research. The participant was a sixth-grade student with learning difficulties, and the "quantitative relation evaluation" of the researcher was used as a participant in the performance of the quantitative relation. The data were collected using visual analysis and C statistics. The results of the study indicated that information technology and inquiring teaching had immediate and maintained effect for the participant on the "overall performance," "graphic pattern," "pattern of number and shape," and "situation of number and shape" in the concept of quantitative relation, and high social validity of effects had been presented.