By Daryl Mellard, Ph.D.
As a result of the 2004 reauthorization of the federal Individuals with Disabilities Education Act (IDEA), public schools may now use new approaches to evaluate a child for specific learning disabilities (SLD). To help parents better understand both the traditional "aptitude-achievement discrepancy" approach, and the newer "responsiveness-to-intervention" (RTI) approach, and how each might affect their child, Daryl Mellard, Ph.D., a principal investigator at the National Research Center on Learning Disabilities, at the University of Kansas, Lawrence, answers some questions about the two approaches. The second article in this series discusses what parents can expect if RTI is implemented at their child's school.
It's interesting to note that reading clinicians used the concept of "less-than-expected" reading achievement before the aptitude-achievement discrepancy approach was linked with SLD (e.g., Franzen, 1920; W.S. Monroe, 1921). Researchers, clinicians, and parents had noted a group of students who were not achieving in a particular academic area at a level one would expect, in comparison to their achievement in other areas. These students had particular deficits, for example, a severe reading deficit, and at the same time showed remarkable strengths or high achievement in other areas. So, the central concepts were underachievement in a specific area of deficit, and strong abilities and skills in other areas. In 1977, when regulations were first adopted for implementing the Individuals with Disabilities Education Act, the method by which SLD would be identified was a controversial issue. Consensus was eventually reached that we would assess students using the aptitude-achievement discrepancy approach, which became the "test" for underachievement in a particular academic area.
The discrepancy approach had advantages from an administrative point of view: The simplicity of the approach made it efficient. One could assess the level of a student's underachievement by administering one or a few achievement tests and comparing a student's scores on the achievement tests to his aptitude score. Such calculations offered an assumed level of precision that had appeal. Both the assessments themselves and the formulas for calculating the discrepancy could look pretty sophisticated, and in many ways they were sophisticated. In our desire to simplify the complex, labor intensive, and costly assessment process, aptitude-achievement discrepancy offered a solution! The model looked good on the surface.
However, in practice, researchers and educators made a terrible mistake in that they failed to realize the limitations of the aptitude-achievement discrepancy. From an SLD perspective, the model was clearly insufficient. A significant discrepancy between a student's aptitude and achievement only indicates the severity of underachievement; it is not a test of SLD. The research literature suggests that students with SLD are underachieving (Swanson, 2000), but not all underachieving students have SLD. A medical analogy might be helpful here. Elevated temperature is a common, measurable symptom of illness. We use a thermometer to check for the discrepancy between a child's temperature and what we consider a normal temperature, 98.6 degrees. All you can say about a child with a high temperature is that, first, he's "hotter" than expected, and further tests are needed to understand why his temperature is high; and, second, an intervention is likely needed.
From a parent's and teacher's perspective, this issue is significant because the scores in a discrepancy calculation do not inform us about any of the underlying basis for the child's underachievement. The discrepancy is the product of a large number of influences, some of which are intrinsic to the student, such as, limited aptitudes for reading acquisition, short attention span, difficulties with pattern recognition, poor working memory, or low self-regulating or self-monitoring performance; and others that are part of the home, instructional, and curricular opportunities, including lack of exposure and practice with pre-academic skills such as rhyming words, inconsistent or insufficient practice with academic skills, lack of a sufficiently organized instructional environment, or changing schools and curriculum due to family relocations. From a teacher's perspective, understanding the basis of the discrepancy is not so important because the major concern is getting the student help beyond what is available in the general education classroom.
Too often in SLD assessments, one finds a discrepancy between a student's aptitude and achievement and jumps to the conclusion that an intervention is necessary. Insufficient time is spent trying to understand the basis for the discrepancy. So, significant errors are likely made in people's good faith efforts to help. Because unless you have a good understanding of the basis of what's causing the discrepancy, you really don't know how to best help a child learn.
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