It's funny, I never read assigned books, or did my home work as a teen (heck, pre-teen). But I was always studying something. All my teachers told my parents the same thing, "Chris could get straight "A"s if he'd just apply himself." The thing was, grades didn't motivate me, an A meant nothing. I'd rather be learning something which interested me. I'd pick up the Math, or English, or whatever as I needed it (to understand my own experiments*, or when writing stories).
*I invented Trigonometry one summer when I was trying to figure out how to programmatically rotate a camera by only using 3D coordinates of it's location, and where it is looking in space.
