The essay topics on the ISEE can really cover any kind of simple, open-ended topic. You might be asked to describe your favorite book or your favorite relative, or you might be asked to describe your dream job or a dream vacation, and so on.
The important thing is that the ISEE essay questions don’t require any outside knowledge, and they don’t have a right or wrong answer. The purpose of the question is to allow you to write an essay in which you choose your own position on the topic and then explain it.
Another important thing to remember is that the ISEE essay isn’t scored. It’s just photocopied and sent to the schools where you apply. Since it’s written in only 30 minutes, a lot of schools might just decide that they don’t care about the essay anyway, because it might not be a good reflection of a student’s writing ability. Of course, if you have any question about how the ISEE essay will be treated by the schools you’re applying to, you should ask the school directly.