I'm not going to even try to debate whether or not you can improve IQ scores by prepping for the test, but since I was the poster who mentioned having a dd who tested gifted at 5 and since then has tested twice at a lower IQ, I wanted to add that in her case, there was no test prep - in fact, we weren't even taking her in for IQ testing, she had an unexpected IQ test as part of a psych work-up for anxiety.
FWIW I had no prep for mine either, which is why I find the topic interesting. I didn't take the WISC though - I was 20 something when I tested (with Mensa - not sure which tests they used - maybe Stanford Binet?) I honestly don't remember - it was, um, a few years ago ;p
