Read the back of your summons. As a student, you can postpone your jury duty till a semester break that is a minimum of two weeks long.
And jury duty isn't that bad, especially in California, since it's a one day / one trial state. Odds are you'll sit in the juror's lounge for a day bored out of your mind. If you're lucky enough to get summoned to a court room, you have the chance to witness, first hand, how inefficiently the legal system works, and the odds are still in favor of you not serving.
Then again, I'm talking about jury duty. I have no idea what Jr. Jury Duty is.