How Are Learning Disabilities Diagnosed?

There are two primary methods of diagnosing a child with a learning disability: the severe discrepancy model, and the response to intervention (RTI) model. The Individuals with Disabilities Education Improvement Act of 2004 (commonly referred to as IDEA, 2004) permits schools to use either method when evaluating a child for special education services. While the severe discrepancy model has historically been used, some schools are now opting for the RTI model. Within IDEA, there are eight types of specific learning disabilities (SLD), in the following areas: oral expression, listening comprehension, written expression (sometimes referred to as "dysgraphia"), basic reading skills, reading comprehension, reading fluency skills (a general term for a reading disorder is "dyslexia"), mathematics calculation, and mathematics problem solving (a general term for a math disorder is "dyscalculia"). Children may be diagnosed with learning disabilities in more than one area.

Severe Discrepancy Model: Sometimes children are tested by a professional at school (typically the school psychologist) and at other times children are tested by a professional outside of school. These evaluators are conducting either psycho-educational assessments or neuropsychological assessments. The evaluator first tests a child's general abilities or intelligence (sometimes called "IQ testing"). These evaluations compare the child's performance to others his or her same age. Next, the child's academic skills are tested. When there is a large gap between the child's ability scores and academic skills, the child might be diagnosed with a learning disorder, if the discrepancy is not better explained by other factors (for example difficulties with attention or understanding the language). The gap between the two types of scores is referred to as a "severe discrepancy." Typically, once a student is classified with a SLD, they are able to access special education services, in which their instruction in the identified area is supported by research-based programs that promote learning.

Response to Intervention (RTI) Model: The RTI model considers how children are responding to interventions that have been put in place (typically research-based programs). Students who are identified as being at risk for learning difficulties (they are struggling within the general curriculum) are provided with supplemental or specialized instruction. Their progress is continuously monitored, and adjustments are made as needed. When a student fails to respond positively to the intervention, they may be diagnosed with a learning disability. Using this model, students are provided with evidence-based interventions before they are technically classified as having a learning disability. It is the failure to make progress with extra support and high-quality instruction that ultimately classifies them as learning disabled.

When classifying a student with a learning disability, there are exclusion criteria that apply. Specifically, if a child's learning difficulties are primarily due to a visual, hearing, or motor disability, intellectual disability, emotional disturbance, cultural factors, environmental or economic disadvantage, or limited English proficiency, then they would not be considered to have a learning disability.