On college applications, the personal statement is the essay that helps a college understand who the student is, how she thinks, what she feels deeply about and what sort of student she would make at the specific school. Each school will ask a different question. It's up to the student to demonstrate an ability to reason, be creative, honest -- and to stand out from the thousands of other statements being read by admissions officers.
We still have a week to go before sophomore year begins, and more than two years before these statements must be submitted. But I am going to suggest that our teen get a head start and list the activities she does, from babysitting and gecko-minding (crickets, anyone?) to places visited, memorable people -- anything that has really meant something to her during the past nearly 15 years.
Meanwhile, here's a helpful site on writing personal statements, for preliminary perusal now, or later.