nition of a severe discrepancy between achievement and intellectual ability, that is, an IQ-achievement discrepancy. Over time, it has become apparent that the use of the IQ-achievement discrepancy has the effect of delaying identification until the child falls below a predicated level of performance. Waiting for a child to exhibit failure sufficient to signal a significant discrepancy between IQ and achievement level takes time. This type of discrepancy cannot be measured until a child reaches approximately age 9 and by that time the student has been experiencing the frustration of academic failure for two to three years. A significant number of epidemiological data show clearly that the majority of children who are poor readers at age 9 continue to have reading difficulties into adulthood (Shaywitz et al., 1999). Thus, a reliance on the IQ-achievement discrepancy, when employed as the principal criterion for the identification of reading disability, possibly harms more children than it helps. Furthermore, good evidence indicates that it is possible to screen children as young as 4-5 years of age and identify those at risk for reading disability, an identification based on poor reading relative to chronological age, that is, poor reading defined solely on the basis of low reading achievement.

The results of several studies indicate that there are no significant differences in cognitive characteristics (other than verbal ability) between children who are poor readers relative only to chronological age (i.e., poor readers defined by low achievement) and children defined as reading disabled on the basis of unexpected underachievement (i.e., on the basis of an IQ-achievement discrepancy) (Fletcher et al., 1994; Stanovich and Siegel, 1994). In addition, neurobiological evidence using sophisticated brain imaging technology supports the cognitive data in indicating similar patterns of brain organization in children defined as having a reading disability on the basis of unexpected underachievement and on the basis of low achievement for chronological age (Shaywitz, B. et al., in press). Important for future policy development, the IQ test results and whether or not a child shows a discrepancy between IQ and reading achievement have little significance for understanding or treating a reading disability.

MENTAL RETARDATION

Disproportionate representation in the mental retardation (MR) category, especially the mild level (MMR), is a long-standing concern in discussions of the participation of minority students in special education (Dunn, 1968; National Research Council [NRC], 1982). Although the numbers of and the degree of disproportionality in minority and nonminority students classified as MR and participating in special education have declined substantially over the past 25 years, the greatest degrees of special education disproportionality continue to occur in this category. Currently,



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