Interviewer will be interested to know what you will be doing other than working at the part-time job. Since you are a student, you can take this opportunity to tell him about your educational goals and what type of coursework you will be engaged in. For example, you could explain, "I would like to get a part-time job so that I can have enough time to complete my educational requirements at the university. I did not feel that working a full-time job would provide me with enough time to get my homework done and attend classes. I will be taking 15 credit hours in pursuit of my business management degree at the local university."