Does anyone have advice about interview essay preperation?

I have an interview set up for a public library position later this month. In their confirmation email there was this: "We expect the interview to begin with a 15 minute set of 2 essay questions, followed by a 45-60 minute verbal interview. You will have time to ask questions of the Hiring Committee after the interview."

I don't think I've ever been asked to answer written essay questions for an interview before. I'll be taking a closer look at the job description for some clues has to how to prepare for this, but I admit I'm surprised and a little flummoxed by it. Have I missed something here, or is this as unusual as it seems to me?