learning disability is defined as a neurological disorder that affects the brain's ability to receive, process, store, and respond to information. They are a group of disorders that can impact many areas of learning, including reading, writing, spelling, math, listening, and oral expression. In the process of identifying learning disabilities, RTI differs from the formerly standard "ability–achievement discrepancy" approach in that decisions are based on outcomes of targeted interventions rather than mathematical discrepancies between scores achieved on standardized assessments. In the RTI process, service delivery is divided into three tiers (i.e., levels) of support, with the intensity of interventions increasing with each level. Tier 1 is focused specifically within the core curriculum, with instruction and interventions targeting all students. Approximately 80% to 85% of the general student body should be able to meet grade level norms without additional assistance beyond the first tier. Students who consistently do not perform within the expected level of performance through Tier 1 instruction are then provided with additional supplementary interventions at Tier 2, which typically involves small group instruction. Approximately 3% to 6% of students will continue to have difficulties after Tier 2 interventions; these students will then receive Tier 3 intervention services, which is the most intense level of intervention (often one-on-one) provided in the regular education environment. Through RTI, educators can get enough evidence-based data to eliminate the possibility that the poor of academic performance is due to the inadequate instruction. Therefore, RTI is a more powerful process to identify whether the students have learning disability. As RTI is a regular education initiative, all three tiers of services are intended to be provided as supplements to, not replacements for, the regular education curriculum; there are some, however, who view Tier 3 as special education. School-wide screening The first level of data collected in the RTI process comes from universal school-wide screenings. These screening assessments are typically given to all students within targeted grade levels, and cover basic academic subjects such as reading and mathematics. Most screening measures aim to be practical and efficient to administer, with the goal of identifying students who may require further assessments and interventions. To evaluate student performance on the screening measures, scores are compared to specific criteria (criterion referenced) or to broad norms (norm referenced). When specific criteria are used, cut scores are established to evaluate students against a specific level of proficiency (e.g., achieving a score