I went to Penn, so I know how tough this supplement is – it’s also a big one! It’s almost like a brand new essay.
The thing is, Penn is really segregated b/w all the different schools. Yes, you can take classes at Wharton while in the College, but the Penn folks still want to know what specific qualities you’d bring to each school.
So, if you’re applying to Wharton, you really MUST talk about your interest in business and then weave in a business anecdote (anecdote part is key). If you’re applying to The College w/ a major in chemistry, talk about why you’re interested in the chemistry and weave in an anecdote that highlights your interest in the subject. Is there a chem class you’re interested in at Penn? A Penn professor?
Then, dedicate the remaining parts of the essay to talk about the Penn “culture” activities you’re interested in. For instance, do you want to be part of the Penn Chess Club? Interested in running w/ the Penn Running Club? This will give the admissions folks a taste of who you are and what you’re interested in.
Here’s more info about how to write the Penn supplement:
http://www.winningivyessays.com/the-3-types-of-admissions-essay-prompts/