Talk to your teachers for extra help, get notecards and make flashcards for all the harder shit you don't remember. Also, doing your homework, homework will maintain your grades at about a C average but tests will bring that down. Or ask your teachers what they base most of the grades on when grading(Tests 50%, quizzes 15%, homework 5%, etc.) and do the things that make up most of your grade. What sucks is, in 8th grade, grades don't count.