In addition to what @YoungThriver posted above, there was a long thread on this last year. FWIW, a few schools also asked us parents that question!
You ask WHY? Here are some thoughts for the 2018-2019 admissions cycle. Let’s imagine you are sitting in the interview session with the AO from “St Prep” boarding school:
- To determine the types of schools you are applying to and level of competitiveness?
- If St Prep is your top choice, reach, or safety?
- Let’s say you are keen on a girls/boys school and state you are most interested in St Prep because it is all female and explain the many advantages of an all female education....then when asked “what other schools are you applying to?”....you list all Co-Ed schools.
- To know TYPE of BS you are interested in or local - if this is just an outlier. For example, if your list is composed of West Coast schools but just for a reach you apply to NE school (St Prep).
- To determine if all the other schools are in Ten Schools?
- To further know HOW MANY schools you are applying to?
- To know if you are smart enough to know how to field, answer, or return this “lob shot” to the back court?
As @skieurope has suggested before, you can use this opportunity to further explain what you are looking for in a school.
Last but not least, maybe the AO is board and just wants to ask the question because they can?