just cut back on the amount you smoke ..if you have a memory issue when smoking just dont smoke before school ..and wait till you have done all your homework before burning one in the eve .. we told our son he can smoke once he is 16 . but only if he has a 3.5 GPA or higher ..you could set a goal to get your self to a lil higher GPA[ your at 2.5 try to get up to 3.0] and if you dont make the goal then maybe try laying off the weed till you can get your grade up ... but i wouldnt try the ritalin thing no good can come from taking speed good luck