I did that until 2 weeks ago, that is the only reason I got into the AP class, my teacher knew I was smart, I just didn't do the work, but now I do and I have done from a 63 to a 91. It is never "I don't understand" it was "I don't know" I did not pay attention in class, I just goofed off and talked to my friends. It seems that I never would until I started failing, but now that I have gotten used to the work i am doing much better.