Establishing proper criteria to determine eligibility for learning disability is important to various services provided to children with learning disability, it is still controversial to diagnose and determine it. Recently highlighted model is RTI(Response to Intervention). However, it is necessary to explore theory for more systematic and precise structure and conduct practical verification constantly in applying the model. Thereupon, this study aims to apply the two tiered － of RTI model to math having the most children below basic level and screen children with learning disability in math showing dual－discrepancy (low performance level and progression). For this purpose, the experiment was conducted to 67 second graders of A Elementary School located in Seoul. The results of study is that one student was screened as learning disability in math. It has verified that children with math learning disability are a heterogeneous group showing different characteristics from underachievers of math in each tier of RTI model and show dual－discrepancy despite the tier－2 intervention, so it is possible to screen children with math learning disability by applying RTI model. Lastly, this paper suggests follow－up research to examine the characteristics of their performance level and progression by grades through applying RTI model to students of different grades.