I honestly wouldn't dwell on the whole "I'm not in a high enough grade," thing. Best thing to do is find scripts that use the functions and pick them apart(this was a lot easier to do way back than it is now, as offline levels had a lot of scripts, and they weren't as overwhelming as they are now adays). You'll soon learn how they work by trial and error and be impressed with yourself. I learned a lot of stuff in Graal before I was ever taught it in a class, such as coordinates(a Graal level is just like a huge graph paper), arrays, problem solving and algorithms'
I mean, it might not apply the same in class, but you'll learn how to use them in Graal, and you won't feel completely out of the loop when you start learning them in school, unlike just about everyone else in your class.