FYI, it sounds like the test he was being administered was the WIAT-III, which is an achievement test, or a supplementary subtest from the WJIIICOG. On the WIAT, the word fluency component score is part of oral expression, which is half of the oral language composite. Not one of the subtests or composites that schools will care a whole lot about. (Definitely the WIAT-III, for you, Chay.) Marnie, in your case, it's not clear whether it was the WJIII Cognitive Extended or the WIAT-III. In the case of the WJIII, it's not a core subtest, and doesn't have to be calculated into the GIA (although it does figure into the GIA-Extended, Thinking Ability-Extended, and Long-Term Retrieval), so I wouldn't worry about it.
Overall, examiners are usually pretty well aware of the kind of noncooperation (not necessarily oppositional, just not-ready-for-testing-today behavior) that preschoolers engage in. I haven't worked in a preschool for a while, but I certainly factored that into my score interpretation when I did. Yes, it will probably skew results a bit, but, no, you don't need to prep him to take it more seriously next time. Sometimes that actually backfires. A good examiner will know how to adapt to the child's developmental level. Plus, there's a lot of rich clinical information to be obtained from the way they do (or do not) test. Viz, Chay, your kid's responses (qualitatively) were a perfect example. A good assessor will use the qualitative performance to illuminate the standard scores.
And, breathe!
