As an 8th grader Big-e, if this is your first experience with learning a sonata, and if you're at an intermediate level, I'd suggest you look first at Beethoven's Opus 49, No. 2 in G. You should be able to learn the whole piece and add it to your repertoire. If, on the other hand, you are quite advanced, then by all means try one of his larger sonatas such as the Pathetique or the complete Moonlight. My point is that you carefully select a work that matches your level of ability so that you can achieve success with it. Remember, it's better to play an easier piece very well than a difficult piece very poorly.