Admissions committees like this question so that they can assess how motivated the student is to attend their school. The applicant should know something about the school and which academic classes, sports, or extracurricular activities he or she might participate in at the school. It's compelling if the student has visited classes at the school or spoken to coaches or teachers to speak in a first-hand, vivid way about why he or she wants to attend the school. Canned, clichéd answers such as, "Your school has a great reputation" or cynical answers like, "My dad said I would get into a really good college if I went here" don't hold much water with admissions committees.