Some of the children who enroll at Walbridge School have had a negative experience with testing at another school. For example, we believe that cognitive ability (IQ) test scores must be carefully interpreted and that much harm can be done if a child is categorized based on a combined test score. While cognitive ability tests are sophisticated measurement instruments, they are too often administered improperly, not following the publisher’s instructions. To illustrate, accommodations must be made for students with learning differences or disabilities. If a child takes longer to process information, time limits need to be removed from the taking of subtests. If a child has fine motor skill or coordination problems, the manipulative subtests should be removed. If the nonverbal and verbal subtest scores vary significantly, combining the two scores provides a statistically meaningless total IQ score; yet this is routinely done. Also, if a child has a high cognitive ability (IQ) composite test score, yet unsatisfactory school performance, this is almost always an indication of a learning difference of the child that may not have been recognized.
Cognitive ability subtest scores can be useful in helping understand how a student learns best. However, in our opinion, the composite IQ test score should never be used to lower expectations for the ability of a child to learn.
Many public school districts use the AAD (Ability Achievement Discrepancy) model when determining the special education resources to be allocated to a child. This may include the use of standardized cognitive ability tests (IQ) to measure the ability of a student to learn. A low composite test score may lead to the conclusion that a student is incapable of making significant progress in school, as there may be a small “discrepancy” between the cognitive ability test score (ability to learn) and the child’s actual school performance. For this reason, it may be decided that few, if any, special education resources will be allocated to support learning.
It is also important to realize that the selection of the standardized cognitive ability test to be administered can make a significant difference in both the subtest and composite scores. The KABC II (Kaufman Assessment Battery for Children II) may be a good choice for a child who has strong nonverbal strengths, but is weak in verbal skills. If the reverse is the case, a student with high verbal skills, but low nonverbal skills, the WISC–IV (Wechsler Intelligence Scale for Children – Fourth Addition) might be a good choice. The WISC-IV is often a good standardized test for children with learning differences or disabilities, as adjustments can be made for slow processing speed, and for significant differences in verbal and nonverbal subtest scores. Using the WISC–IV Technical Report #4 (2005, revised 2008) allows for the calculation of an alternative “composite” score, the General Ability Index (GAI). The Wisconsin Department of Public Instruction accepts the GAI, although, in our experience, many school districts don’t use this measure of learning ability that favors many children with learning differences and disabilities.
At Walbridge, we don’t administer cognitive ability tests (IQ), although we will look at the subtest scores of previously administered tests for insights into the learning strengths of a child. We do use the Iowa Tests of Basic Skills (ITBS), not a cognitive ability test, to provide a baseline to measure a child’s academic progress. The ITBS is administered when a child is enrolled, and at the end of each school year. The results are used to document the academic advancement of each student. More importantly, ITBS results are used to guide the individualized instruction for each of our students. The use of this standardized test is not to categorize the academic level of a student, but to improve our instruction and to provide each family with a measure of their child’s progress.
If a child with learning differences or disabilities has a low composite IQ test score, the results should be carefully reviewed by a testing expert. Parents should challenge results that may not reflect the true ability of their child to learn, and ask that a new test, perhaps the WISC–IV with a GAI composite score, be given and administered, with needed accommodations approved by the publisher.