Don't forget that IQ test scores depend in large part upon what your child had for breakfast, what the tester had for breakfast, and what the test authors had for breakfast.
The book NurtureShock describes several scientific studies which prove, despite legions of well-meaning parents and the whole self-esteem cult, that telling and praising children for being smart effectively makes them less smart because they don't learn how to work through challenges and failure.
I LOVE that book. I am annoyed I got it for my Kindle, because I want it in my "real" library of dead tree books!
