Train yourself not to check the clock a lot. Many individuals who want to make time pass by faster constantly stare at the clock on the classroom wall. Instead of wearing a watch, rely on the clock on your portable media player or phone, if your school allows one, to keep track of time between classes. That way, you'll have to manually pull your phone out of your pocket, rather than check your wrist, and won't be tempted to look at the clock all the time.
Set up a weekly reward for yourself. This might be as inexpensive as milkshake at the local ice cream shop or a movie at the theater. If you're on a tight budget, try to pick something that you can pay for with less than $10 per week so that you spend less than $100 in the nine weeks. Reward yourself on Friday night after school or on Saturday. Keep the reward as close to the end of your school week as possible to train your mind to accept the reward as part of the work you did in the week.
Pick a moderately challenging project to work on in your free time each week that will be finished in nine weeks. This might be a productive project that you can build or sew, or you might choose a 1,000-piece puzzle to put together, 25 pieces or so per day. Whatever you pick, you want to look forward to doing it when you finish your homework or come home from school. Do not work on this project on the weekend.
Get a study buddy to help you study for nine weeks only. Don't make them commit to studying with you for the whole year, just for nine weeks. This gives you both an attainable goal and might help you both improve your grades and better understand your work.
Pick something to reward yourself with at the end of the nine-week period. You could plan a party, invite friends to go out for laser tag, go to a theme park or even buy the new video game you've been saving up for. Try to pick this reward before the nine weeks start or within the first few weeks so you can look forward to it.