Or rather how much do we actually remember it? I basically use all of my elementary math schools, reading, writing, and I'm occasionally interested in science and social studies,.. but I sort of made a point to throw out the stuff I didn't need and I'm doing fine. Too much knowledge on the brain isn't good anyways lol (Not to mention the fact that even though I believe that they can coexist I was forced to learn about being evolved from apes and that part is just utterly ridiculous to me.)