Question about the 8th grade leadership team.?

Unfortunately, you are right that these things often turn into popularity contests. It's good that the school is asking you to write since that may weed out some of the people who aren't truly interested. Try to figure out issues that are important to lots of students at your school that you could do something about on the leadership team, and mention those in your paper. If you're allowed to make it longer, you might want to - 100 words isn't very much to explain about why you're a good candidate. Hopefully the other students will see that you are committed and interested and will vote for you.