I don't know if it is school specific, but one of the supplemental essays offered at my top school was about service and the question specifically was about a community / group i either am a part of or support, what I give that community, and what I get out of that community. I handled this mixing personal goals in with my work experience, and I think it was a good mix of learning about me as the applicant as well as demonstrating my work history in action. Hope this helps and if I am wrong, anyone feel free to chime in !