I remember being in "honors" classes in junior high and high school. One of my best friends was at the opposite end of the spectrum. He took remedial English and math and struggled with those. We both had muscle cars, I had a 71 Chevelle and he had a 74 Nova SS. I could do basic stuff, oil change, valve cover gaskets, etc. When it came to rebuilding the carb, he knew what to do and didn't need to follow instructions. He was "dumb" when it came to IQ tests but a genius when it came to practical applications and therein lies the worthlessness of IQ tests. They're great if you want to measure one's ability to solve those types of problems, but they're far from conclusive.