Responsiveness to Intervention (RTI) refers to the methodology that is used to determine how slow is slow (rate of growth) and how low is low (student’s level of performance), as an alternative to ability-achievement discrepancy within a comprehensive Specific Learning Disability Determination process. Common RTI methodologies include Rate of Improvement, Student Growth Percentiles, and Mastery Measurement.
Pennsylvania refers to this alternative as the “RTI Approach” to evaluating Specific Learning Disabilities and has developed a tool that assists interested schools to evaluate fidelity of implementation of their MTSS for the use of the RTI approach for Determination of Specific Learning Disabilities (SLD).