Welcome,
IQ tests tell us something, but they are really just a fuzzy snapshot of a particular child at a particular time. Especially before age 6 or 7, they are not highly exact instruments (I think I read somewhere that about 30% of the kids who test at 4 into the NYC gifted program would not qualify at age 6 - but I don't know if that is accurate). Your own observations, the child's achievement, persistence, focus, all sorts of things come into play eventually and likely influence whether a child is "gifted." Is your son reading yet? Have you looked at the indications of giftedness listed here:
http://talentigniter.com/ruf-estimates There is a saying "gifted is as gifted does." If you feel like what you are seeing is gifted, try to encourage it regardless of what a test score tells you.
It is hard when the test is high stakes, and a school decision rests upon it. I have to say I am really against prepping a kid for an IQ test, but I understand why people in NYC feel like they must.
If you retest your son at age 6, would you be able to apply for the special school again, and move in at that point? I am not sure about the WPPSI, but I believe on WISC a child isn't supposed to repeat the test for two years.
It is terrific that your son is so curious and interested in what he is learning - whether technically gifted or not, this trait will take him a long way, and it sounds like you are doing a great job encouraging him to explore his interests.
Good luck, Cat
