CogAT, NNAT and WISC: what parents should know before a test
Intelligence tests are given to children for two very different reasons, and the reason decides whether preparation makes sense. One reason is diagnosis: a child struggles in school and a test is meant to show where strengths and weaknesses lie. The other is selection: a gifted programme, a school or a scholarship admits only children above a certain score. In the first case the test should measure the current state. In the second, preparation is what everyone does who knows the procedure.
The common tests
- CogAT (Cognitive Abilities Test). The most widely used group test in the United States for gifted-programme screening, with a verbal, a quantitative and a nonverbal battery. The nonverbal battery consists of figure matrices, figure classification and paper folding.
- NNAT (Naglieri Nonverbal Ability Test). Purely figural, used for the same selection procedures, especially where language should play no role.
- OLSAT (Otis-Lennon School Ability Test). Verbal and nonverbal, used by many districts alongside or instead of the CogAT.
- WISC-V (Wechsler Intelligence Scale for Children). The standard in clinical and school psychology, for ages six to sixteen. Ten core subtests in about an hour, including matrices, digit span, vocabulary, picture concepts and symbol search. Administered individually by a psychologist.
- WPPSI for preschoolers from two and a half, with the same principles and more playful materials.
- Raven CPM and SPM. Figure matrices in colour for younger and standard form for older children, used as a screening tool in many countries.
What the results mean
An IQ score in a child is a snapshot with a measurement error of about five points in either direction. Results before school age are not very stable; afterwards they become more reliable, but shifts of ten points between age ten and adulthood are normal. For diagnosis the total score is not the interesting part, the profile is: a child with high matrix performance and a low digit span needs something different from a child with the reverse profile.
What preparation achieves
For selection procedures the same applies as for adults: familiarity with the item format raises performance. In children the effect tends to be larger, because many have never seen a matrix before the first test and spend part of the time working out what the task is. The meta-analysis by Hausknecht et al. (2007) shows a gain of about a quarter of a standard deviation for cognitive ability tests from repetition alone.
In the United States this has produced a market for CogAT and NNAT preparation, and school districts know it. Not preparing means competing against prepared children.
For a diagnostic evaluation the opposite holds. Coaching a child before the WISC distorts the profile and leads the psychologist to wrong conclusions. The WISC subtests are also copyrighted and unpublished precisely so that this does not happen.
How parents can prepare sensibly
- Item types, not test questions. Matrices, figure series, classification, digit span. The child should know what a matrix is and how to approach it, not memorise specific items.
- Short and regular. Ten minutes a day over three weeks beats two hours on a weekend. Children under ten do not concentrate longer, and the test itself is short.
- Explain, do not grade. After every item, name the rule. "The shape stays the same across the row, the count goes up to the right." That is the part that transfers.
- Time pressure last. First the item types without a clock, in the final week with a time limit. Time pressure without understanding produces only stress.
- Do not turn the test into an event. Children who believe everything depends on it perform worse. The test is an hour of solving puzzles, nothing more.
What does not help
Brain-training apps with points, levels and rewards train what they show and, according to the research, do not transfer to intelligence tests, see Can you train your IQ? With children there is the added problem that the game mechanics replace the goal: they collect stars instead of understanding rules. Plain items with explanations suit children from about eight better than one would think, because they mirror the test itself and leave no surprise. The item types in detail: how to solve matrix reasoning and aptitude test preparation.
Frequently asked questions
Should you prepare a child for the CogAT or NNAT?
For gifted-programme screening, yes. Familiarity with the item types is common and fair, and unprepared children compete against prepared ones. For a diagnostic evaluation, no, the test should measure the current state.
What is on the CogAT?
Three batteries. Verbal (analogies, sentence completion, classification), quantitative (number analogies, puzzles, series) and nonverbal (figure matrices, figure classification, paper folding).
How long should a child practice?
Ten minutes a day for about three weeks. Short sessions with explanations after each item, a time limit only in the last week.
IQ Prep drills exactly these item types under test conditions, with an explanation after every answer. Free to try, full version $4.99 one time, no subscription.
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