A Mathematician's Lament, by Paul Lockhart. Also, i'm not completely sure about this, because i had to have my eyes a bit open to understand it. But would be nice to had readed it in my sixteens.

Basically, one of the important ideas i saved was; If you want to learn something, don't just simply study. First, find a problem that care you, then try to solve it, last, study how to actually solve it, maybe existed a better way that you could use for your next try, making easier to you to understand everything related to that problem and say with confidence you learned; maybe didn't existed a better way, and you can share and discuss your solution achieving a better one.

Find problems, solve them, make them easier, learn.

Then, make that general for all your life problems, not only those science related ones.